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Messenger no144 Messenger no144 Document Transcript

  • Astronomy in BrazilScience impact of HAWK-IMid-infrared imaging of evolved starsThe Carina dwarf spheroidal galaxy The Messenger No. 144 – June 2011
  • The OrganisationBrazil’s Route to ESO MembershipAlbert Bruch11 Laboratório Nacional de Astrofísica – LNA, Itajubá, BrazilOn 29 December 2010, in a ceremonyheld at the Ministry of Science andTechnology in Brazil´s capital, Brasília,the then Minister, Sergio MachadoRezende and the ESO Director GeneralTim de Zeeuw signed the accessionagreement by which, pending ratifica-tion by the Brazilian Congress, Brazilbecomes the 15th ESO Member Stateand the first non-European member.An overview of the historical back-ground, the current state of astronomyin Brazil, and the motivation that madeBrazil apply to become an ESO MemberState is presented. Figure 1. A contemporary engraving by Zacharias 1919 in Sobral, Ceará, which contributed Wagener of a building in 17th century Recife thatHistory decisively to the first observational proof may have hosted the first astronomical observatory in the Americas. for Einstein´s theory of general relativity.The signature of the accession agree­ment to ESO (see de Zeeuw, 2011) is the Astronomy began to establish itself inlatest highlight in Brazilian astronomy’s Janeiro (Videira, 2007), and is shown in other Brazilian institutions in the latevery long and distinguished history, which Figure 2. It was originally meant to 19th century and this progressed, primar­goes back much further than most non- provide essential services to the newly ily in the universities, and most notablyBrazilian astronomers are aware. Long founded state such as time-keeping, in São Paulo and in Porto Alegre, at abefore Brazil was established as a state, and fundamental scientific research in rather modest pace during much of theat a time when various European pow- astronomy only gradually became part 20th century. Astronomy in Brazil hasers still disputed dominion over its vast of its activities. Arguably the observa- only really taken off during the past threeexpanses, Brazil hosted the first astro­ tory’s most notable scientific achieve­ or four decades. The three main factorsnomical observatory, not just in the ment was the organisation of the expe- that have contributed to this substantialAmericas, but also in the southern hemi­ dition to observe the solar eclipse of and very successful increase are:sphere. In 1639 the German naturalist andastronomer Georg Marcgrave foundedan observatory in Recife (Prazeres, 2004), Figure 2. The early MAST home of the Observa­which was then the capital of a Dutch tory Nacional in Rio decolony. The probable appearance of this Janeiro, photographedobservatory is shown in Figure 1. Should in 1921, which todaywe consider this as the first “European hosts the Museum of Astronomy and RelatedSouthern Observatory”? Sciences.However, troubled times and warfarebetween the countries disputing he-gemony over the rich Brazilian coloniesimpeded the long-term survival of theseinitial astronomical activities and astron­omy only took firm root in Brazilian soilafter the country became an independentempire in 1822. On 15 October 1827,the Emperor Dom Pedro I established theinstitution that has now evolved into theObservatório Nacional (ON) in Rio de2 The Messenger 144 – June 2011
  • 1. New funding lines that permitted LNA promising Brazilian students to receive their professional education abroad, mainly in Europe and in the USA.2 Newly created graduate courses in astronomy, meaning that scientists could be trained in Brazil, taking advantage of the expertise brought back by others who had obtained their degrees in foreign countries.3. The creation of the Observatório do Pico dos Dias (OPD) and the installation of a medium-sized (at the time) tele­ scope which gave the growing astro­ nomical community access to a com­ petitive observational infrastructure for the first time.The above-mentioned factors resultedin the dramatic growth of Brazilianastronomy, both in terms of the numberof scientists, as well as in scientific out­put. It quickly became evident that the Figure 3. Aerial view of the OPD, the principal obser­ purchase has proved to be a severe limi­ vatory on Brazilian territory, located in the Serra daavailable instruments were insufficient to tation. Brazil currently owns 2.5% of Mantiqueira in the southern part of the State of Minassatisfy the rapidly growing demand and Gerais, operating a 1.6-metre telescope (main build­ Gemini. In 2010 it purchased additionalthat there is no really good site for a ing) and two 0.6-metre telescopes. observing time from the United Kingdom,modern optical observatory in Brazil. So, increasing its access to the telescopesinstead of enlarging the existing facili- angle formed by the cities of São Paulo, by a factor of two and it is anticipated thatties at a location that is far from ideal for Rio de Janeiro and Belo Horizonte was Brazil will increase its share in Gemini toastronomical observations, and following chosen as a compromise between easy about 6 % after 2012, when the UK leavesthe modern trend towards the globali­ accessibility and good observing con­ the partnership.sation of science, it was recognised that ditions. The observatory is operated byinternational collaborations were the the National Astrophysical Laboratory With abundant access to rather smallright way forward for the further develop­ (Laboratório Nacional de Astrofísica telescopes (OPD) and limited access toment of astronomy in Brazil. [LNA]), based in Itajubá, Minas Gerais, big telescopes (Gemini), the Brazilian which is a research institute of the Minis­ astronomical community felt the need for try of Science and Technology, and is something in between: a decent amountInfrastructure for astronomical research responsible for providing the optical of time at an intermediate-sized tele­ astronomical infrastructure to the entire scope. So Brazil joined forces with threeSo as to make telescopes and instru­ scientific community. Today the OPD US institutions (NOAO, University of Northments with a wide range of apertures, hosts three telescopes with apertures Carolina and Michigan State University)characteristics and capabilities avail- between 1.6 metres and 0.6 metres, and to build and operate the SOAR Telescopeable to Brazilian astronomers, Brazil it is equipped with an instrument suite (Southern Astrophysical Research Tele­became a partner in the Gemini Obser- that is tailored to serve its users well. An scope), located next to Gemini South onvatory, the SOAR Telescope and finally effort to upgrade the observatory is Cerro Pachón (see Figure 4). SOAR isentered into a Cooperative Agreement underway to keep it competitive, despite a 4.1-metre telescope that is optimisedwith the Canada–France–Hawaii Tele­ the increasing light pollution and the for high image quality. Brazil enteredscope (CFHT), giving Brazilian astrono­ growing number of other facilities that are this consortium as the majority share­mers access to a range of facilities now open to Brazilian astronomers. holder with a stake of about 34%. Brazil­besides the Brazilian OPD. ian astronomers also have access to The Gemini Observatory operates two the 4-metre Blanco Telescope at CTIOBrazilian observational optical astronomy 8-metre-class telescopes on Hawaii through an agreement with NOAOtakes place primarily at the OPD (shown (Mauna Kea) and in Chile (Cerro Pachón) about the exchange of observing time,in Figure 3). When the observatory was on behalf of a consortium of seven which complements the services andplanned in the 1970s, logistical consider­ countries. Although very well used by instruments offered by SOAR.ations demanded that the observatory Brazilian astronomers, and extremelywas built within easy reach of the big important for the development of optical The cooperative agreement with thepopulation centres where most astrono­ astronomy in Brazil, the rather small CFHT, which is located on Mauna Kea,mers were located. A site within the tri- share of Gemini that Brazil was able to Hawaii, is meant to provide access to a The Messenger 144 – June 2011 3
  • The Organisation Bruch A. et al., Brazil’s Route to ESO Membership Figure 4. The 4.1-metre highly productive wide-field 4-metre-classSOAR Inc. SOAR Telescope on telescope with competitive instruments in Cerro Pachón, Chile. the northern hemisphere. The agreement is limited in time and will be reviewed, with the aim of potentially renewing the contract, in 2012. Brazilian participation in all these interna­ tional observatories is managed by the LNA, which thus exercises a key role in optical astronomy in Brazil. Apart from these installations, which are open to the entire astronomical community, some institutions operate their own facilities on a more modest scale, and these either serve a specific scientific purpose or con­ centrate on education and outreach. The most recent and arguably most im­ portant (and certainly the biggest) of these is IMPACTON, a robotic one-metre telescope for observations of near- Earth objects, which is currently being commissioned by the Observatório Nacional, and is located in the interior of Pernambuco State. Other areas of astronomical research have also benefitted from Brazil’s contributions to international projects and collaborations. These include space astronomy (Brazil is a partner in the CoRoT space mission, and it is also engaged in the PLATO mission), high energy astrophysics (through the partici­ pation of Brazil in the Auger experi- ment), and cosmology (Brazilian institu­ tions are members of the International Center for Relativistic Astrophysics Net­ work [ICRA-Net]).José-Williams Vilas-Boas The growing importance of large sur- veys and the exploitation of data banks for astronomical research has been recognised and has led to the recent cre­ ation of the Brazilian Virtual Observatory (BraVO), as the national branch of the International Virtual Observatory Alliance. BraVO unites researchers from various institutions in a coordinated effort to cre­ ate infrastructure and tools for data- mining and to disseminate the concept of the Virtual Observatory in Brazil. In parallel, the LIneA (Laboratório Interinsti­ tutional de e-Astronomia) collaboration is formed by scientists working at three research institutes of the Ministry of Sci­ ence and Technology (MCT) to develop Figure 5. The dome of the Itapeninga Radio Obser­ the infrastructure and software to store vatory (ROI) in Atibaia, São Paulo. and process large astronomical datasets. 4 The Messenger 144 – June 2011
  • Figure 6. Mounting the for Gemini, where it was responsibleLNA 1300 optical fibres of for the fibre feed between the telescope the SOAR Integral Field Spectrograph at the and the bench spectrograph (although, LNA Optics Laboratory. unfortunately, through lack of funding the instrument was never built). In a success­ ful attempt to find a place on the interna­ tional market for astronomical instrumen­ tation, the LNA has also built the fibre feed for the Frodospec spectrograph at the Liverpool Telescope on La Palma. Independent efforts in instrument devel­ opment are ongoing at the Observatório Nacional, which, in collaboration with the IAG, is building a camera for the J-PAS (Javalambre Physics of the accel­ erating Universe Astrophysical Survey) project in Spain. Facilities for instrumen­ tation development are also being Radio astronomy, which was already the Earth from space), a group at INPE installed at the Federal University of Rio comparatively well developed before the is currently building MIRA X, a small Grande do Norte in Natal. steep increase in optical astronomy ac- survey satellite to observe the spectral tivities began, has not followed the same and temporal behaviour of a large num­ steeply rising path. Apart from some ber of transient X-ray sources. Moreover, Size of the Brazilian astronomical modest investments in specialised instru­ INPE is collaborating with the LNA and community ments operated by small groups, no the Instituto de Astronomia, Geofísica e major effort has been made to provide Ciências Atmosféricas (IAG) of the Uni­ According to a census (updated in 2010), access to a competitive infrastructure for versity of São Paulo to develop the Brazil­ there are 341 fully trained and active the general community. The Itapeninga ian Tunable Filter Imager (BTFI), which astronomers (i.e. with a PhD) in Brazil (up Radio Observatory (ROI; Figure 5), lo- is an innovative camera and integral field from no more than a handful some cated in Atibaia, some 50 kilometres from spectrograph for the SOAR telescope. 40 years ago). This workforce is comple­ São Paulo, and operated by the Nacional Other long­term collaborations between mented by 313 postgraduate (Master’s Space Research Institute (Instituto INPE and LNA on instrumentation for the and PhD) students. Thus, more than Nacional de Pesquisas Espaciais [INPE]) OPD are also ongoing. 650 scientists are active in astronomical is the only instrument available to all research. While there is a concentration astronomers. This 18–90 GHz, 14-metre In the past, instrumentation develop- of astronomers in a few universities antenna has not had a major upgrade ment at LNA was rather modest and and federal research institutes, the num­ since it was built in 1974. Access to more restricted to immediate OPD needs. But ber of groups in other places is rapidly modern equipment would be very during the past decade much effort increasing as a result of the policy of the much welcomed by the radio­astronomy has been invested in turning such activi­ federal government to strengthen sci- community. ties into one of the fundamental pillars ence and higher education in less well­ of the institute. The LNA has built labora­ developed parts of the country. In conse­ tories and workshops, and provided quence, astronomy is being pursued Instrumentation them with state-of-the-art equipment, today in 46 institutions (… and counting), with a special emphasis on optical metro- which are widely spread across Brazil. The desire to participate in both scientific logy and the handling of optical fibres While many of the smaller groups are part research in astronomy and in techno­ for astronomy (see Figure 6 as an exam­ of physics or other related university logical development has led to the imple­ ple). In collaboration with the IAG and departments, postgraduate education in mentation of the necessary infrastruc- other university institutes, the LNA has astronomy is offered in 19 institutes. ture to build astronomical instruments for built SIFS, a 1300-channel integral field use at international observatories, such spectrograph (currently being commis­ There is not enough room here to char­ as SOAR. These efforts are concentrated sioned at the SOAR Telescope). It is also acterise all these institutes in detail. at the LNA and INPE, in collaboration constructing the SOAR Telescope Echelle However, it may be worthwhile to briefly with the universities and other scientific Spectrograph (STELES) and is planning enumerate the most important. With institutions. a similar instrument for the OPD. The the IAG (see Figure 7), the University of LNA was a member of the winning team São Paulo hosts the dominant research While most of the activities in instrument in an international competition for the institute in astronomy in the country. It development at INPE are related to fields detailed design study of the Wide Field is home to about 20% of the total work­ other than astronomy (e.g., observation of Multiple Object Spectrograph (WFMOS) force mentioned above. This is twice The Messenger 144 – June 2011 5
  • The Organisation Bruch A. et al., Brazil’s Route to ESO Membership Figure 7. Urania, the Muse of Astron­ (instrument development among them), omy, from a picture window in the come from the same sources, including library on the former campus of the Institute of Astronomy and Geophysics the government funding agency FINEP of São Paulo University. (Financiadora de Estudos e Projetos), as well as from Brazilian state funding agencies, which normally do not fund the operation of astronomical infrastruc­ ture. While other states also contribute, FAPESP, the funding agency of São Paulo state, plays a dominant role. CNPq (Conselho Nacional de Desenvolvi­ mento Científico e Tecnológico), a branch of the MCT, is extremely important as a provider of stipends for students and grants for established scientists. A similar role is played by CAPES (Coordenação de Aperfeiçoamento de Pessoal de Nível Superior), a branch of the Ministry of Education. Apart from stipends and grants, CNPq also finances smaller scale projects for individual scientists, scientific meetings, etc. (as do the state agencies).as many as the second most important, the end of the 1960s, but as the number Specific funding by the federal and statethe venerable Observatório Nacional in of active astronomers has increased, a governments, such as PRONEX (Pro­Rio de Janeiro. Strong astronomy groups steep and continuing rise in the number grama a Núcleos de Excelência) and thecan also be found at INPE, located in of published papers has been observed Millennium Institutions (Institutos doSão José dos Campos, the Federal Uni­ (Figure 8). The role of Brazil as a signifi­ Milênio) in the past, and the current (vir­versity of Rio de Janeiro (distributed cant producer of scientific papers was tual) National Institutes of Science andbetween the Observatório do Valongo and recognised when it became a member Technology (INCT) has also greatly bene­the Department of Physics), the Federal of Astronomy and Astrophysics, the lead­ fited Brazilian science. Two astronomy-University of Rio Grande do Sul in Porto ing astronomical journal in Europe. related National Institutes have been cre­Alegre and the Federal University of Rio ated: INCT-A (A for astrophysics), whichGrande do Norte in Natal. While all these Although optical and infrared observa­ focuses on preparing the astronomicalastronomy centres carry out research tional astronomy is predominant, Brazil­ community for the challenges and oppor­in many fields, the Brazilian Centre of ian astronomy embraces a wide range tunities of the future, and INCT-E (E forPhysical Research (Centro Brasileiro de of special fields. There are at least 16 espaço [space]) which focuses on spacePesquisas Físicas [CBPF]), Rio de Janeiro, major areas of astronomy that are being technology and astronomy from space.which hosts the Brazilian branch of ICRA- actively pursued by astronomers in Brazilnet, focuses mainly on cosmology. and that have recently been identified Direct personnel costs are, of course, car­ in the context of a National Plan for ried by the employers, who are, in mostAdministratively, the numerous astron­ Astronomy1. The relative importance of cases, the federal or the state govern­omy groups are distributed between the various disciplines can be gauged ments. However, the private sector is alsogovernment institutions, which are from the number of publications that they involved through private (in general, non-directly subordinated to the federal Minis­ have generated. Table 1 gives the per­ profit) universities with research and highertry of Science and Technology (CBPF, centages of papers by Brazilian authors education interests in astronomy.INPE, LNA, ON), entities belonging to in refereed journals by area in 2008.federal or state universities, and (increas­ingly) private universities. Long­term strategic outlook FundingThe community founded the Brazilian Brazil’s young and vigorous communityAstronomical Society (Sociedade Brazilian astronomy is largely publicly feels that it has gained an internationalBrasileira de Astronomia [SAB]) in 1974. financed. Operating costs for facilities reputation as a respected player in globalThe Society currently has 678 members. open to the entire community are borne astronomy. It is not seen as an accident exclusively by the Federal Government, that Rio de Janeiro was chosen to hostAs measured by the number of publi- normally through MCT research insti­ the IAU General Assembly in 2009, butcations in refereed journals, scientific tutes. Funds for the development of rather as recognition of the achievementsproductivity was all but non-existent until new projects and capital investments of Brazilian science. The community is6 The Messenger 144 – June 2011
  • Publications in refereed journals by guaranteeing access to the future generation of giant telescopes, i.e. the 300 European Extremely Large Telescope, and opening up opportunities for 250 Brazilian industry to take part in its development and construction; 200 – it provides access to ALMA, satisfying and fostering the development of a 150 community of radio astronomers who have not benefited from significant 100 investments similar to those made in optical astronomy during the past three decades; 50 – it opens up a wide range of opportuni­ ties for the participation in technological 0 development as part of the instrumen­ 1970 1975 1980 1985 1990 1995 2000 2005 2009 Year tation programme for ESO telescopes.Figure 8. Evolution of the number of publications by Among many other issues, this docu­ It is felt that the development model forBrazilian astronomers in refereed journals over the ment emphasises the need to maintain optical astronomy which Brazil haspast decades. access to a competitive observational followed in the past, i.e., offering its sci­ infrastructure, on penalty of losing the entists a suite of instruments with diverseaware that worldwide astronomy respected position gained by Brazilian characteristics on small and medium­is characterised more than ever by inter­ astronomers. Different ways of achieving sized telescopes up to to the 8-metre-national collaborations. Consequently, this purpose have been studied by the class Gemini giants, although with limitedsuccess for a national community de- INCT-A and a special commission cre­ access in the case of the larger instru­pends decisively on its participation in ated by the MCT. Based on these results ments, has lifted the astronomical com­the international community. the broad majority of the astronomical munity to a level of maturity. This pro­ community came to the conclusion that gress now permits the next step — orMoreover, it is understood that the grow­ the association of Brazil with ESO would rather leap — in its evolution: the ascenting necessity for international collabo- be the most effective of all the available to a new and higher level in scientific,rations, the numerous scientific opportu­ options. More than any other alternative, technological and instrumental terms,nities that present themselves in the the association with ESO benefits the which is expected to be the natural con­worldwide scenario, combined with the country in many ways, the most impor­ sequence of Brazil’s association withelevated costs for large-scale scientific tant advantages being that: the strongest organisation in ground­projects, call for a medium- and long- – it gives Brazil immediate access based astronomy in the world. We areterm strategic plan for astronomy to to ESO’s existing telescopes, fostering confident that not just optical astronomydirect and coordinate the further develop­ scientific collaboration (and competi­ will be strengthened, but that the fertilement of the field in Brazil. Therefore, tion!) with scientists of other member environment of partnership with ESOwith the active support of the Ministry of states, and enlarging the scope of will benefit Brazilian astronomy as aScience and Technology, in 2010 the instruments already at the disposal of whole, as well as related technologicalcommunity elaborated a National Plan for Brazilian astronomers significantly, fields.Astronomy1 as a guideline for the future thus eliminating some limitations felt byof astronomy in the country, aligned to parts of the community;the general policy for science and tech­ – it meets one of the main recommenda­ Referencesnology of the federal government. tions of the National Plan for Astronomy de Zeeuw, P. T. 2011, The Messenger, 143, 5 Prazeres, A. 2004, Georg Marcgrave, e o desenvolvimento da astronomia moderna naOptical and infrared stellar astronomy 28.8 % Table 1. Percentage of papers pub­ América Latina, na cosmopolita Recife de Nas-Theoretical cosmology 17.4 % lished in refereed journals by area in sau, http://www.liada.net/NASSAU%20&%20 2008. GEORG%20MARCGRAVE.pdfOptical and infrared extragalactic astronomy 11.9 % Videira, A. A. P. 2007. História do ObservatórioPhysics of asteroids 5.8 % Nacional: a persistente construção de uma identi-Theoretical stellar astrophysics 4.3 % dade científica. Río de Janeiro: ObservatorioChemical evolution of stellar systems 4.3 % NacionalDynamical astronomy 4.3 %Solar radio astronomy 3.2 % LinksInstrumentation 3.2 % 1Exoplanets 2.7 % National Plan for Astronomy: http://www.lna.br/ PNA-FINAL.pdfOther 13.2 % The Messenger 144 – June 2011 7
  • Telescopes and Instrumentation The first European ALMA antenna from the AEM Consortium (Thales Alenia Space, European Industrial Engineering and MT-Mechatronics) being carried on an ALMA transporter during the handover to the ALMA Observatory at the Operations Support Facility (OSF). After testing at the OSF, it will be moved to the ALMA Operations Site on the Chajnantor plateau. See Announcement ann11022 for more details.
  • Telescopes and InstrumentationThe Science Impact of HAWK-IRalf Siebenmorgen1 in one-hour on-source integration are: summer of 2008. The instrument alsoGiovanni Carraro1 23.9 in J, 22.5 in H and 22.3 in Ks. suffered from radioactive events whichElena Valenti1 contaminated two of the four chips ofMonika Petr-Gotzens1 The efficiency, defined as the proportion the detector mosaic (Finger, 2008). TheGabriel Brammer1 of photons converted into electrons contamination can be seen in the darkEnrique Garcia1 passing the telescope, instrument optics exposures. One of the four detectorsMark Casali1 and detector, is computed for various shows on average a well­localised decay near-infrared (NIR) instruments and is every 75 s. The event affects an area shown in Figure 1 for the NIR cameras of 7 × 7 pixels and is eliminated by a1 ESO SOFI, VISTA, ISAAC, CONICA and cleaning algorithm in the pipeline. Another HAWK-I. The efficiency of the HAWK-I detector is similarly affected, and, al- instrument is 70–80 % and so it is the though the events are much less frequent,HAWK-I is ESO’s most efficient near- most efficient NIR camera in ESO’s instru­ they generate charge which is not local­infrared camera, and after two and mentation suite. The stability of the zero ised to within a few pixels, but spreads ina half years of operations we review its point is important for absolute photom- a diffuse charge cloud with an unpre-science return and give some future etry. For HAWK-I, there is a small periodic dictable location, resulting in glitches thatdirections in the context of the Adaptive scatter in the zero point of Δ J ~ 0.1 mag cannot be cleaned during data analysis.Optics Facility. The instrument under- over a period of a year, significantly lower However, the sensitivity limit of the indi­went major technical challenges in the than that of either CONICA or ISAAC. vidual detectors shows that there is noearly phase of its operations: there major degradation of the detection limitwas a problem with the entrance win- Along with the distortion caused by the caused by these radioactive events.dow, which was replaced, and radio- instrument optics, atmospheric refrac-active events occur in the material of tion produces a geometrical shrinkage of The HAWK-I instrument team has recentlytwo of the four detectors. A number of the field of view with increasing zenith undertaken observations to assess thehigh quality science papers based on distance. The differential achromatic re- relative sensitivities of the four HAWK-IHAWK-I data have been published, indi- fraction is ~ 0.6 arcseconds, as measured detector chips, using observations of thecating a good performance and scien- over the full 7.5 by 7.5 arcminute field size high Galactic latitude field around thetific return. HAWK-I is well-suited for a of HAWK-I and for a zenith distance z = 2.7 quasar B0002-422 (α 00h 04m 45s,variety of attractive science cases and between 0° and 60°. δ -41° 56; 41?) taken during technicala project is in development to provide time. The observations consisted of foura faster readout, which would improve During science operations three techni- sets of 11 × 300 s sequences in thethe capabilities for Galactic observa- cal challenges were identified: the en- NB1060 filter; details of such an obser-tions. When combined with the laser- trance window, radioactive events in the vational set-up are discussed in theassisted ground layer adaptive optics detector material and the instrumental HAWK-I User Manual. The four sequencessystem, HAWK-I will become an excel- distortion correction. The instrument was are rotated by 90° in order that a givenlent facility for challenging follow-up first installed in July 2007. At the begin­ position on the sky is observed by eachobservations of exoplanetary transits. ning of the observing period P81 in 2008 of the four chips of the HAWK-I detec- the instrument suffered from a damaged tor. The jitter sequences are reduced fol­ coating of the entrance window. This lowing the standard two-pass back­Instrument overview and performance defect was fixed by a replacement win­ ground subtraction work flow described dow installed during an intervention in the in the HAWK-I pipeline manual. ObjectsHAWK-I is a cryogenic wide-field camerainstalled at the Nasmyth A focus of theVLT Unit Telescope 4 (UT4). The field of | | Figure 1. Comparison courtesy P. Hammersley of the efficiency of theview is 7.5 by 7.5 arcminutes, with a cross- Y J H Ks NIR instruments SOFI,shaped gap of 15 arcseconds between 0.8 VISTA, ISAAC, CONICAthe four 2RG 2048 × 2048 detectors. and HAWK-I is shown.The pixel scale is 0.106 arcseconds. The 0.6 Efficiencyinstrument is offered with ten filters intwo filter wheels: four broadband filters(Y, J, H and Ks), which are identical to 0.4the filters used in VIRCAM/VISTA, and HAWK-Isix narrowband filters (Brγ, CH4, H2, CONICA 0.2 ISAAC1.061 μm, 1.187 μm, and 2.090 μm). The VISTAimage quality is seeing-limited down to SOFIat least 0.4 arcseconds. Typical limitingmagnitudes (Vega) to reach a signal-to- 1.0 1.5 2.0noise ratio (S/N) of five on a point source Wavelength (µm) The Messenger 144 – June 2011 9
  • Telescopes and Instrumentation Siebenmorgen R. et al., The Science Impact of HAWK-I 16 AOF and GRAAL 1. Galaxy evolution from deep multi- CHIP 1 colour surveys; 14 CHIP 2 The Adaptive Optics Facility (AOF; see 2. Multi-wavelength observations of 12 Lelourn et al., 2010; Paufique et al., 2010 normal and active galaxies; CHIP 3 and Arsenault et al., 2010) will provide a 3. Structure and evolution of nearbyN mag –1 arcmin – 2 10 CHIP 4 correction of the ground layer turbulence, galaxies; Coadded stack improving the image quality of HAWK-I. 4. Galactic star and planetary formation; 8 The resulting point spread function (PSF) 5. Outer Solar System bodies. 6 diameter that collects 50 % encircled energy is reduced by 21% in the Ks­band, HAWK-I started to operate regularly in 4 and by 11% in the Y­band, under median April 2008. A significant number of seeing conditions at Paranal of 0.0.87 arc- observations executed during P81 were 2 seconds at 500 nm. Hence, the AOF will affected by the damaged entrance 0 provide better seeing statistics. When window coating, and were re­executed 13 14 15 16 17 18 19 installing the AOF on UT4, the secondary by ESO. In the period from mid-2008 MAG_APER (D = 1.8 , ZP = 25) mirror of the telescope will be replaced until end of 2010, 26 refereed papers by a deformable secondary mirror (DSM) were published containing HAWK-IFigure 2. Number counts as a function of aperture with more than 1000 actuators. In addi­ results. They have 350 citations to datemagnitude of the four HAWK-I detectors: chip1 (red tion, four laser guide stars will be installed and an h-index of 10. Of these 26line), chip2 (orange), chip3 (green), chip4 (blue line)and the co-addition of all four chips (black line). on the telescope structure, and a wave­ papers, two were published in Nature,Dashed lines give the number of spurious detections. front sensor system, GRAAL (ground seven in ApJ, four in ApJ Letters, one inRadioactive events are most common for chip 2, layer adaptive optics assisted by lasers), AJ, four in MNRAS, and 12 in A&A. Thewhich nevertheless has a similar detection probabil­ will be used to measure the turbulence two Nature papers, Tanvir et al. (2009)ity as the other chips, but an enhanced number ofspurious detections at faint flux (> 17 mag) levels from artificial guide stars. GRAAL will be and Hayes et al. (2010), resulted in ESO(shown as dashed orange). installed between HAWK-I and the press releases. To evaluate the science Nasmyth flange. HAWK-I’s field of view is impact of HAWK-I, we have compared not affected by GRAAL. It is planned to the number of papers based on data begin installing the AOF in 2013, with a obtained at the other NIR VLT instruments total telescope downtime of a few months during their first 2.5 years of science (subject to the exact distribution of tech­ operations. The rate of publication turnsare detected using the SExtractor soft­ nical time) due to the installation of the out to be fairly similar among all theware. The resulting number counts as new secondary mirror, the lasers and VLT instruments considered (NACO,a function of aperture magnitude ob- GRAAL. The schedule anticipates that ISAAC, SINFONI and CRIRES). The sci­served by each detector are shown in the AOF will be operational from 2015. ence output of HAWK-I up to the endFigure 2. The limiting magnitudes, here of 2010 can be summarised as follows:taken to be the magnitude where the Normal adaptive optics systems aim 1) In most cases, publications which arenumber counts in Figure 2 decrease at correcting atmospheric turbulence based on HAWK-I present results onsharply, provide a proxy for the individual down to the diffraction limit of the tele­ extragalactic, high redshift astrophys­detector sensitivities. The sensitivities scope. The price to be paid is a limit in ics. The most relevant papers beingagree to within 10 % between the individ­ corrected field of view (less than 1 arc­ the characterisation of the galaxy pop­ual chips. We also show in Figure 2 minute) and a limit in sky coverage (less ulations around z ~ 2 (Galametz et al.,the number counts for a deep co-added than 50 %) since a bright guide star is 2010; Hayes et al., 2010; and Lidmanstacked image of the four rotated and required even when using laser guide et al., 2008) and beyond redshift z ~ 6aligned jitter sequences which are a fac­ stars. The AOF ground layer adaptive (Vanzella et al., 2010; Fontana et al.,tor of two deeper than the individual optics mode (GLAO) does not provide 2010; Castellano et al., 2010a,b; andsequences. We used the co-added stack diffraction-limited image quality, but it Bouwens et al., 2010). Such a burstto assess the number of spurious does correct the full 7.5 by 7.5 arcminute of results for extremely high redshiftsources detected on each individual de­ field of view and the sky coverage is targets was not expected at the timetector: objects matched from the single practically 100 %. when defining the HAWK-I sciencechip image to the deeper image are cases, while the results at intermediateconsidered to be real, while objects that redshifts were expected from scienceonly appear on the single chip images HAWK-I science return case #1.are considered spurious. The image arte­ 2) The other fields explored so far arefacts on detector 2, which are caused When HAWK-I was conceived, the Milky Way stellar populations (Brasseurby radioactive events, do result in an ele­ selected science cases, according to et al., 2010), trans-Neptunian objectsvated number of spurious detections the document, Science Case for (Snodgrass et al., 2010), gamma-rayat faint magnitudes, reaching 20 % at the 0.9–2.5 μm infrared imaging with the bursts (D’Avanzo et al., 2010) and qua­limiting magnitude. VLT (ESO/STC-323), were: sars (Letawe & Magain, 2010). Stellar10 The Messenger 144 – June 2011
  • population studies have been ham­ Figure 3. Three colour ESO/M. Gieles, Acknowledgement: Mischa Schirmer (J [1.25 µm], H [1.65 µm] pered by HAWK-I’s large minimum and Ks [2.15 µm]) com­ detector integration time (DIT), which posite maps obtained causes saturation on bright sources with HAWK-I. The upper and almost completely prevents ob- image shows the nearby galaxy Messier 83, total servations in the Galactic disc. exposure time was 8.53) No papers were published in the field hours and field of view of star formation and structure of 13 arcminutes squared. nearby galaxies (science cases #3 and On the bottom, an image of 6 by 5.2 arc­ #4) in the period up to and including minutes of two stellar 2010, in spite of the fact that several clusters in the Carina programmes have been queued and Nebula is shown, successfully executed. obtained during HAWK-I science verification.4) Contrary to expectations, HAWK-I was intensively used to study exoplanets, via transit or occultation techniques (Gibson et al., 2010; Anderson et al., 2010; and Gillon et al., 2009), and to conduct supernova search campaigns (Goobar et al., 2009) for spectroscopic follow-up. Transit observations, in particular, are expected to be increas­ ingly important in the nearby future as a windowed readout of the detec­ tors has been implemented.5) The majority of the observations pub­ lished require or benefit from the large field of the instrument.In Figure 3 we give two examples of JHKscolour-composite maps highlightingthe superb image quality of the HAWK-Icamera.Future directions: HAWK-I + GRAALIt is anticipated that HAWK-I will beequipped with GRAAL and routinely op-erate in GLAO mode from 2015 onwards,which will open up new paths forcompetitive science cases in the comingyears. The image quality delivered byHAWK-I + GRAAL is expected to be 20 %better in comparison with today. Forseeing in the Ks-band of 0.6 arcseconds,the GRAAL-supported instrument isexpected to deliver a resolution of mum, FWHM) on point sources larger good seeing conditions for NACO and0.5 arcseconds on a regular basis. Given than 0.6 arcseconds. This arises from the SINFONI. Observing with HAWK-IHAWK-I’s pixel scale of 0.106 arcseconds, fact that 70 % of the HAWK-I observa­ together GRAAL will result in a muchthe PSF delivered by HAWK-I + GRAAL tions were executed during DIMM (differ- better image quality performance. Thewill still be Nyquist-sampled, which ential image motion monitor) seeing question arises: what kind of scientificis particularly important for precise PSF- worse than 0.83 arcseconds. Half of the projects will be feasible with HAWK-I +photometry, astrometry and the analysis HAWK-I observations were performed at GRAAL that are currently not feasibleof morphological structures on sub- a median DIMM seeing of almost 1 arc­ with HAWK-I, or only under very rare con­arcsecond spatial scales. Currently, half second. The poorer than average seeing ditions, when the seeing is exceptionallyof the HAWK-I Ks­band images show conditions prevalent during most HAWK-I good. We outline three selected sciencean image quality (full width at half maxi­ observations is a result of the demand for cases of HAWK-I + GRAAL. The Messenger 144 – June 2011 11
  • Telescopes and Instrumentation Siebenmorgen R. et al., The Science Impact of HAWK-I1. Cosmological surveys HAWK-I instrument operation team is at to be followed up around stars signifi­A deep, wide-field NIR imaging survey present testing a new windowed detec- cantly fainter than those observed at thecomplementing the HST/CANDELS cos­ tor readout scheme that allows very short moment (Ks of 8–11 mag). Therefore amological survey is required. CANDELS1 exposure times on the brightest pixels larger volume of planet–host star systemsis the largest single project in the history and, in parallel, long exposures for the re- can be probed, so that potential exoplan­of the Hubble Space Telescope, with maining field. Such a new detector read­ ets detected by CoRoT come within902 assigned orbits of observing time out mode in combination with HAWK-I + reach of the VLT and hence provideand obtains images at J­ and H­band GRAAL’s improved seeing capabilities important NIR constraints on the physicalover a total field of view of 30 × 30 arc­ should lead to an increase of HAWK-I ob- nature of the planets. Observations withminutes. The survey will be completed in servations in this research field. VISTA will not have the required sensi-2014. As the scientific exploitation also tivity to perform such investigations.relies on multi-colour imaging, HAWK-I + Since the large field of view is importantGRAAL is an ideal instrument to com- 3. Exoplanets and transits for precision photometry, there is noplement the survey with very deep Ks­ HAWK-I has recently proved to be an strong advantage in using JWST/NIRCamand Y­band imaging, as well as with nar­ excellent instrument with which to instead.rowband imaging aimed at searching perform challenging observations of exo­for very high redshift galaxies. Morpho­ planetary transits. In order to obtain anlogical studies of galaxies at intermediate overall picture of an exoplanet’s atmos­ Referencesand high z are a particular goal of the pheric properties, occultation data in Anderson, D. R. et al. 2010, A&A, 513, 3project that can be pursued only with a many photometric bands are required. Arsenault, R. et al. 2010, The Messenger, 142, 12spatial resolution of < 0.5 arcseconds With a continuously growing number of Bakos, G. A. et al. 2011, AAS Meeting 217, 253.02over a wide area. A wide field of view is newly discovered planets and planetary Bouwens, R. J. et al. 2010, ApJ 725, 1587 Brasseur, C. A. et al. 2010, AJ, 140, 1672essential in such a study, since structural candidates, there is a high demand for Cameron, A. C. et al. 2009, IAU Symposium,properties are analysed on sufficiently comprehensive follow-up observations by Volume 253, 29large statistical samples. HAWK-I obser­ NIR imaging. Crucial requirements for Castellano, M. et al. 2010a, A&A, 511, 20vations in the Y-band, complementing such observations are a wide field of Castellano, M. et al. 2010b, A&A, 524, 28 Coppin, K. E. K. et al. 2010, MNRAS, 407, L103the first two CANDELS fields, have already view, allowing for a large number of refer­ D’Avanzo, P. et al. 2010, A&A, 422, 20been scheduled. ence sources for precise relative photom­ Decarli, R. et al. 2009, ApJ, 703, L76 etry, and an instrument sensitive enough Finger, G. Reports on HAWK-I detectors available at:VISTA does offer the requested wide-field to collect a sufficient number of photons, http://www.eso.org/~gfinger/marseille_08/AS08- AS12-9_H2RG_mosaic_gfi_final.pdfcapability, but delivers neither the spa- typically for a S/N > 1000, in a short time. http://www.eso.org/~gfinger/hawaii_1Kx1K/cross­tial resolution nor the required sensitivity. From space the CoRoT satellite (Moutou talk_rock/crosstalk.pdfIn order to reach the same limiting mag­ et al., 2008) is a mission particularly Fontana, A. et al. 2010, ApJL, i725, 205nitude, VISTA requires an integration time designed to discover transiting Galametz, A. et al. 2010, A&A, 522, 58 Gibson, N. P. et al. 2010, MNRAS, 404, L10416 times longer than HAWK-I + GRAAL. exoplanets. CoRoT has already found Gillon, M. et al. 2009, A&A, 506, 359However, the NIRCAM2 instrument several hundred systems with candidate Gogus, E. et al. 2010, ApJ, 718, 331onboard JWST will have a field of view transiting planets. The mission will Goobar, A. et al. 2009, A&A, 507, 71almost six times smaller than HAWK-I, but continue beyond 2015 and will possibly Greiner, J. et al. 2009, ApJ, 693, 1610 Hayes, M. et al. 2010, Nature, 464, 562will offer at least a factor 15 in improved be followed up by PLATO (Roxburgh Hayes, M. et al. 2010, A&A, 509, L5sensitivity. JWST is expected to become & Catala, 2006), an ESA project study Hickey, S. et al. 2010, MNRAS, 404, 212operational in ~ 2016. due to be launched in 2018. Similarly, Le Louarn, M. et al. 2010, SPIE, 7736, 111 from the ground, there are robotic search Letawe, G. & Magain, P. 2010, A&A, 515, 84 Lidman, C. et al. 2008, A&A, 489, 981 projects ongoing on small telescopes. Mattila, S. et al. 2008, ApJ, 688, L912. Nearby wide-field imaging Instrumentation includes wide-field imag­ McLure, R. J. et al. 2010, MNRAS, 403, 960Stellar population studies, both in nearby ing capabilities covering several degrees Moutou, C. et al. 2008, A&A, 488, L47galaxies and in Galactic fields, currently in optical bands. The goal is to discover Paufique, J. et al. 2010, SPIE, 7736, 57 Roxburgh, I. W. & Catala C. 2006, IAUJD, 17, 32suffer most from crowding and will bene­ a large sample of candidate planetary Snodgrass, C. et al. 2010, A&A, 511, 72fit from an improved Ks image quality transits which will be followed up on Stanishev, V. et al. 2009, A&A, 507, 61provided by HAWK-I + GRAAL. High spa­ larger telescopes by radial velocity stud­ Tanvir, N. R. et al. 2009, Nature, 461, 1254tial resolution coupled with a wide field ies or NIR imaging. Examples are: WASP Vanzella, L. et al. 2010, ApJL, 730, 35of view is an important requirement for (Cameron et al., 2009) which has alreadystellar population studies. A problem of detected 16 systems and will continue Linkscurrent HAWK-I observations, when tar­ for several years; or HAT-South, which is 1geting crowded stellar populations, is that the first global network dedicated to CANDELS: www.candels.ucolick.org 2 JWST NIRCam:the relatively large minimum DIT of 1.7 s search for transiting planets. www.ircamera.as.arizona.edu/nircamcauses saturation on the brightestsources, which are numerous when ob­ The increase in sensitivity of HAWK-I +serving towards the Galactic disc. The GRAAL will allow exoplanetary transits12 The Messenger 144 – June 2011
  • Telescopes and Instrumentationp3d — A Data Reduction Tool for the Integral-fieldModes of VIMOS and FLAMESChrister Sandin1 Feature ESO pipelines p3d Table 1. Comparison between features of p3dPeter Weilbacher1 Logging, at different levels of verbosity x x and the IFU modes ofOle Streicher1 Configuration by a plain text file x x the ESO VIMOS (versionCarl Jakob Walcher1 Combination of raw-data images partly all recipes 6.2) and FLAMES (ver­Martin Matthias Roth1 Dark current subtraction x – sion 2.8.7) pipelines. Spectrum extraction: regular/deconvolution methods x/– x/21 Spectrum extraction: Leibniz-Institut für Astrophysik Potsdam subtraction of a scattered-light component – x (AIP), Germany Fully automatic spectrum tracing x x Creation of a dispersion mask automatic interactive Flat-field normalisation partly xThe second release of the data reduc- Flux calibration x –tion tool p3d now also supports the Full error propagation partly xintegral-field modes of the ESO VLT Interactive inspection of intermediate andinstruments VIMOS and FLAMES. final products – xThis article describes the general capa- Reduction using a GUI/scripts x/x x/xbilities of p3d and how its differenttools can be invoked, with particularreference to its use with data from using the DCR program (Pych, 2004) first, solution to the problem. p3d comes withVIMOS and FLAMES. and thereafter, if required, combining an integrated spectrum viewer that the resulting images in p3d using an works with any IFU (row-stacked) spec­ average. All extracted images of p3d are trum image, together with a fibre positionp3d is a general and highly automated accompanied by an error image. table.data reduction tool for fibre-fed integralfield unit (IFU) spectrographs. Based By default p3d shows graphical results The algorithms used in p3d are describedon an early proprietary version, p3d was of the spectrum tracing, the cross- in Sandin et al. (2010). With this newrewritten from scratch to be more ver- dispersion profile fits (used later when release all parts of p3d are now thoroughlysatile, user-friendly, extendable and deconvolving overlapping spectra), the documented. The installation procedureinformative (Sandin et al., 2010). The first quality of the dispersion solution, and is described in the distribution READMErelease supported four IFUs: the lens the optimally ex tracted spectra. Figure 1 file, and the various recipes are, togetherarray and PPAK of the PMAS spectro­ shows an example. This makes it easy with all the options, described in detailgraph at the Calar Alto Observatory; to check that the outcome is correct and in the headers of the respective files. ASPIRAL at the AAOmega spectrograph satisfactory; and if it is not these plots more appealing version of the same doc­at the Australian Astronomical Observa­ will quickly provide important clues for a umentation is available at the projecttory; and VIRUS-P at the McDonaldObservatory. The second release of p3dsupports most of the remaining instru­ments, including the four higher resolu­tion IFU modes of VIMOS (HR-Blue,HR-Orange, HR-Red, and MR), as well asall the setups for the three IFU modesof FLAMES (ARGUS, and the two sets ofmini IFUs).Data reduction featuresAll the reduction capabilities of p3d, withsupporting test studies, are describedin detail in Sandin et al. (2010). p3d itselfis available at the project website1. InTable 1 we outline the available featuresof p3d and the two ESO pipelines for Figure 1. The fitted cross-dispersion line profiles for a set of the spectra in the VIMOS fourth quadrantVIMOS (version 6.2) and FLAMES (i.e. (with grism HR-orange). The different lines are: inten­GIRAFFE; version 2.8.7). Cosmic-ray hits sity (in raw counts) at the middle column of the bias-in single images, or in images that cannot subtracted continuum image (black line); the fittedbe combined, are not removed by p3d. Gaussian profiles (blue lines); the initial position of each spectrum (vertical red lines); and the vignettedInstead, for ESO data, we recommend spectra, which were not fitted (vertical blue lines). The Messenger 144 – June 2011 13
  • Telescopes and Instrumentation Sandin C. et al., p3d — A Data Reduction Tool<ob900000.sh> <ob900000.pro>#!/bin/bashcpath=`pwd` cd,cur=cpathpath=”/data/user/VLT-P87/C/2011-04-27” path=’/data/user/VLT-P87/C/2011-04-27’cd $path cd,cpathname=”ngc1-hr-blue-T1-1a” name=’ngc1-hr-blue-T1-1a’parfile=”${p3d_path}/data/instruments/vimos/nvimos_hr.prm” parfile=!p3d_path+’/data/instruments/vimos/nvimos_hr.prm’userparfile=”../p3dred/user_p3d.prm” userparfile=’../p3dred/user_p3d.prm’opath=”../p3dred/odata/$name” opath=’../p3dred/odata/’+namemkdir -p $opath file_mkdir,opathdf1=” df1=[, $VIMOS_IFU_OBS117_0001_B.1.fits.gz, ‘VIMOS_IFU_OBS117_0001_B.1.fits.gz’, $VIMOS_IFU_OBS117_0002_B.1.fits.gz, ‘VIMOS_IFU_OBS117_0002_B.1.fits.gz’, $VIMOS_IFU_OBS117_0003_B.1.fits.gz, ‘VIMOS_IFU_OBS117_0003_B.1.fits.gz’, $VIMOS_IFU_OBS117_0004_B.1.fits.gz” ‘VIMOS_IFU_OBS117_0004_B.1.fits.gz’]group=1,1,1,2 # Files 1-3 are combined, file 4 is used single group=[1,1,1,2] ; Files 1-3 are combined, file 4 is used single# Extracting the object spectra for quadrant 1: ; Extracting the object spectra for quadrant 1:logfile=”../p3dred/logs/dred_${name}_objx_q1.log” logfile=’../p3dred/logs/dred_’+name+’_objx_q1.log’masterbias=”../p3dred/odata/VIMOS_SPEC_BIAS118_0001_B_mbias1.fits.gz” masterbias=’../p3dred/odata/VIMOS_SPEC_BIAS118_0001_B_mbias1.fits.gz’tracemask=”${opath}/VIMOS_IFU_LAMP118_0001_B_imcmb1_trace1.fits.gz” tracemask=opath+’/VIMOS_IFU_LAMP118_0001_B_imcmb1_trace1.fits.gz’ dispmask=”${opath}/VIMOS_IFU_WAVE118_0001_B.1_dmask1.fits.gz” dispmask=opath+’/VIMOS_IFU_WAVE118_0001_B.1_dmask1.fits.gz’flatfield=”${opath}/VIMOS_IFU_LAMP118_0001_B_imcmb1_flatf1.fits.gz” flatfield=opath+’/VIMOS_IFU_LAMP118_0001_B_imcmb1_flatf1.fits.gz’${p3d_path}/vm/p3d_cobjex_vm.sh $df1 $parfile masterbias=$masterbias p3d_cobjex,df1,parfile,masterbias=masterbias, $ tracemask=$tracemask dispmask=$dispmask flatfield=$flatfield tracemask=tracemask,dispmask=dispmask,flatfield=flatfield, $ userparfile=$userparfile opath=$opath detector=0 userparfile=userparfile,opath=opath,detector=0, $ logfile=$logfile loglevel=2 group=$group & logfile=logfile,loglevel=2,group=group# Click away the popup window (for a 1600x1200 screen):sleep 1 && xdotool mousemove 800 600 && xdotool click 1 Figure 2. An example of a script that can be used to extract object spectra in VIMOS data. The script on the left-hand (right-hand) side is used from the shell (IDL command line).website1; these web pages are updated after any change to the procedure or the are all traced well, without any requiredwith each new release. code. Figure 2 shows an example of a user interaction. The third quadrant simple script, using both methods, which sometimes requires a manual parameterp3d is based on the Interactive Data can be used to reduce VIMOS data. adjustment to trace all the spectraLanguage (IDL)2, which must be installed properly; this is caused by the spectrumon the system. All computing platforms pattern, which is less well defined thansupported by IDL can be used with p3d. Details regarding VIMOS and FLAMES in the other quadrants. The tracing plotsThere are three ways to invoke p3d. The show that the tracing procedure some­first is through the graphical user inter­ When p3d is used with FLAMES and times misses one spectrum in the lastface (GUI), which can be started either VIMOS some care is required in the group of spectra. With pre-refurbishmentfrom the IDL command line or using the configuration procedure to produce the data, a similar problem is only found inshell script provided. This approach cor­ most accurate outcome possible. We data from the fourth quadrant. The scat­responds to the ESO tool Gasgano. The emphasise that the required modifica­ tered­light subtraction should be usedsecond is to run the individual recipes tions are small when comparing data in all spectrum extraction procedures tofrom the command line, and the third is that were extracted either before or set the zero background level properly;to use the shell scripts provided; this last after the respective refurbishments (cf. we recommend a zeroth-order polyno­approach most closely corresponds to Hammersley et al., 2010; Melo et al., mial fit.the ESO tool Esorex. The shell scripts use 2007). Here we note the details of eachthe IDL Virtual Machine together with the instrument separately, beginning with We found that the first-guess dispersioncompiled binary files that are provided, VIMOS. solution of p3d allows the emission lineswith or without an IDL license. The shell that are required to create an accuratescripts work on all platforms with a bash VIMOS dispersion mask to be easily identifiedshell. With VIMOS data the reduction is done for all grism setups and quadrants. For for each of the four quadrants individually. our data from P86 (PI: Lundqvist), theThe GUI method is an easy entry point The data from the four quadrants are maximum residual (for HR-blue and HR-for the new user. By comparison, the two combined in a final step — after the data orange) between the true wavelengthscript methods allow the more experi­ have been flux calibrated — to produce and the fitted wavelength of any arc lineenced user to save time, since she or he a datacube image with all 1600 spectra. was 0.002–0.007 nm for a fifth-ordercan simply execute the scripts anew, Data from quadrants one, two and four, polynomial. Larger residuals are found in14 The Messenger 144 – June 2011
  • Figure 3. The p3d spectrum viewer showing anextracted datacube, where all four quadrants ofVIMOS have been combined. The four different pan­els show: the spectrum image (upper left); the spatialmap at a selected wavelength (upper right; north isup and east left); ten stored spatial maps of differentwavelengths (middle panels); the selected spectrum,in this case the average of the 33 spectra that aremarked in the spatial map (bottom panel).low-transmission spectra. We also found The data were not flux-calibrated, but the strict the set of arc lines to the brightestthat the highest accuracy level can be data from the separate quadrants were before the reduction is begun. In ourachieved in more spectra if cosmic-ray re-normalised using the mean flat-field data from P83 (programme ID 083.B-hits are removed in the arc image before spectrum of each quadrant. 0279, PI: Neumayer), the maximum resid­creating the dispersion mask. ual, between the true wavelength and FLAMES the fitted wavelength of any arc line, isNoise reduction is a good reason to The three different IFU modes of FLAMES constant at about 0.005–0.006 nm, for areplace an extracted flat-field image with use the same instrument configuration fourth-order polynomial using about 20a smoothed version. Such a replace- file. Since there is only one detector, all lines and the LR02 setup. While the fring­ment proved impossible with VIMOS, due spectra are reduced at once. We have ing effects in the red wavelength rangeto the strong fringing at red wavelengths. found that the tracing works well in all are lower with the refurbished instrumentWith the new data the fringing effects cases, although the last sky fibre is than previously, one should still notare smaller, but still present. The default always outside the CCD. The calibration smooth the flat-field data to remove theis therefore to avoid any smoothing of the fibres are reduced along with the other fringes more completely.flat-field image. Moreover, if twilight flat- fibres, but are never used by p3d. Fur­field images are available, it is possible to thermore, p3d provides a linear first- Our reduced data of the nuclear regionuse their transmission correction and guess dispersion solution for the same of the galaxy NGC 3621 were fitted withcorrect the data further. In Figure 3 we set of arc lines that is used by the stellar population models and are shownshow the spectrum viewer display for an GIRAFFE pipeline. However, in order to in Figure 4; specifically we used the pixel-extracted and combined dataset of a enable easy identification of all the arc fitting code PARADISE (Walcher et al.,supernova remnant (using HR-orange). lines to be used, it is advisable to re­ 2009), as well as a preliminary version of The Messenger 144 – June 2011 15
  • Telescopes and Instrumentation Sandin C. et al., p3d — A Data Reduction Tool Figure 4. A spectrum of VIMOS–IFU (Monreal-Ibero et al., 2005). the circum­nuclear disc While the new version of p3d already of the galaxy NGC 3621. 10 The data (black line) are contains a high level of functionality, there fitted with a stellar pop­ are many features that could still be ulation model (red line). included. For example, flux calibration,Fλ The blue line is the con­ automated dispersion-mask creation, and 5 tinuum used to normal­ ise the data. Yellow an integrated line-fitting tool. With suffi­ areas mark wavelengths cient interest from the community we masked from the fit. would consider adding full support also 0 The lower panel shows for the two remaining fibre-fed IFUs, viz. 4100 4200 4300 4400 4500 the fit residuals. Wavelength (Å) IMACS (Magellan) and Integral (WHT). Hδ Hγ OIII Acknowledgements 2 We thank Peter Lundqvist and collaborators forResid Fλ providing us with data from the refurbished VIMOS instrument (programme ID 086.D-0992). 1 References 0 González-Lópezlira, R. A. et al. 2010, MNRAS, 403, 1213 4100 4200 4300 4400 4500 Hammersley, P. et al. 2010, The Messenger, 142, 8 Wavelength (Å) Markwardt, C. B. 2009, ASP Conf. Ser., 411, 251 Melo, C. et al. 2007, The Messenger, 133, 17 Monreal-Ibero, A. et al. 2005, ApJ, 628, L139the Charlot & Bruzual (in prep.) stellar profile-fitting stage in p3d makes use of Pych, W. 2004, PASP, 116, 148 Roth, M. M. et al. 2004, ApJ, 603, 531population model (see Gonzalez et al., modern multi-core workstations for Sandin, C. et al. 2010, A&A, 515, A352010). The lower panel shows the resid- improved processing speed. Instrument- Walcher, C. J. et al. 2009, MNRAS, 398, 44uals of the fit, i.e. a pure emission line specific guidelines on how to tailor thespectrum. Note the presence of [O iii] at extraction are provided on the p3d Wiki3. Links436.3 nm and of Wolf–Rayet featuresat 415–422 nm. This plot demonstrates 1 p3d project website: http://p3d.sourceforge.net.the excellent quality of the data and of the Outlook 2 IDL can be downloaded free from:reduction procedure, allowing even the http://www.ittvis.com. 3 p3d Wiki: http://sourceforge.net/apps/mediawiki/faintest features to be identified reliably. The old version of p3d has already been p3d/index.php?title=Main_Page used successfully to reduce and publishBoth VIMOS and FLAMES benefit from data from various instruments (Roth et al.,optimal extraction. The associated 2004) — including first data from the MPG/ESO 2.2-metre telescope image of the spiral galaxy NGC 3621 taken with the Wide Field Imager (WFI). NGC 3621 is a nearby Sd galaxy with a high inclination, situated at a distance of 6.2 Mpc. The centre hosts a Seyfert 2 active galactic nucleus and a nuclear star cluster. The colour image was formed from broad-band (B, V and R) and narrowband ([O iii] and Hα) images selected from the ESO archive by Joe DePasquale as part of the Hidden Treasures competition (Hainaut et al. 2011, The Messenger, 143, 57). See image eso1104a for more details.16 The Messenger 144 – June 2011
  • Telescopes and InstrumentationPhase 3 — Handling Data Products from ESO PublicSurveys, Large Programmes and Other ContributionsMagda Arnaboldi1Jörg Retzlaff1Remco Slijkhuis1Vincenzo Forchí1Paulo Nunes1Diego Sforna1Stefano Zampieri1Thomas Bierwirth1Fernando Comerón1Michèle Péron1Martino Romaniello1Dieter Suchar11 ESOPhase 3 represents the final step inthe execution of ESO large programmesand public surveys, which starts withthe submission of the letters of intentfor public surveys and proposals forlarge programmes, i.e. Phase 1, andcontinues with the preparation and Figure 1. Summary of the regions of the sky covered publication/availability of these products by the six VISTA surveys: VHS is shown as the bluesubmission of observing blocks for ser- to the ESO community. As part of the shaded areas; VIKING areas in light green; VVVvice mode observations, i.e. Phase 2. areas in light blue; VMC areas in purple; and the implementation of the Council’s recom­In this paper we present the new Phase ULTRAvista and VIDEO fields in red and yellow, mendations, a dedicated group within the3 infrastructure deployed on 10 March respectively. Data Products Department (DPD) was2011. This infrastructure supports the set up to oversee the definition of thereception, validation and publication of scopic public surveys and the selected requirements for Phase 3 and their imple­data products from the public survey projects will soon follow the same mentation for the validation, ingestionprojects and large programmes to the policies and procedures for telescope and publication of data products from theESO Science Archive Facility. operations, access to data products various ESO projects in the SAF. The and publication. Phase 3 tools, user manuals and defini­ tions of data standards are all availableAccess to the survey data products by The raw data collected at the survey on the ESO website1.the astronomical community telescopes for the different projects amounts to about 700 GB per month, The dependencies between telescopeThe ESO public survey projects on which in turn are condensed into a few time allocation and the delivery of datathe near-infrared 4-metre VLT Infrared terabytes of data products each year. products to the ESO SAF is made explicitSurvey Telescope for Astronomy (VISTA) Because of the legacy value of the public in the policies for public surveys. In fact,(Emerson et al., 2006) and the optical survey projects, ESO’s policy is to en- further allocation of observing time at the2.6-metre VLT Survey Telescope (VST) sure their long­term archival value by survey telescopes beyond the first year(Capaccioli et al., 2005) are ambitious supporting easy access to the data prod­ and a half, and the scientific follow-up atprojects that range from very wide area ucts and fostering their wide scientific the VLT of the public survey targets issurveys with short exposures, like the use by the astronomical community at subject to timely delivery of the surveyVISTA Hemisphere Survey (VHS), which large, beyond those projects initially iden­ products and their compliance to theaims at covering the whole southern tified by the survey teams. specifications detailed during Phase 1.hemisphere, to deep surveys concen- The Public Survey Panel that initially tooktrating on small areas or even a single part in selecting the public survey pro­pointing on the sky, and going very deep. Phase 3 policies and concepts jects will periodically review the progressTypical examples of the latter are the of the surveys and report to the OPCUltraVISTA and VIDEO surveys (for an Policies for any additional allocation of telescopeoverview of the six VISTA and the three As stated in the ESO Council document time to these projects.VST public surveys see Arnaboldi et on the VLT/VLTI science operation poli­al. [2007]). A plot reproducing the survey cies (Meeting#104, 17–18 December Conceptsareas of the six VISTA surveys is shown 2004), the ESO Science Archive Facility The Phase 3 concepts provide the frame­in Figure 1. In addition to the imaging (SAF) is the collection point for the sur- work that supports the data submis-surveys, ESO opened a call for spectro­ vey products and the primary point of sion process and facilitates data access The Messenger 144 – June 2011 17
  • Telescopes and Instrumentation Arnaboldi M. et al., Phase 3 — Handling Data Products and spot checks of the metadata content Phase 3 and the reported quality parameters are Programme carried out. A summary diagram of the Phase 3 process and the various respon­ sibilities is shown in Figure 3. Data Data Data Tools Collection A Collection B Collection C The Phase 3 infrastructure consists of the following components: — a web application — the Phase 3 release manager — that allows the Release 1 Release 2 Release 3 Release 1 Release 2 Release 1 PI to manage the Phase 3 delegation, and define collections and releases; — the release validator, which is a com­Figure 2. Block diagram illustrating the hierarchy of Phase 3 process and tools mand-line application that verifiesthe Phase 3 concepts: from Phase 3 programme to the data standard and validity of thecollection and data release. The Phase 3 process consists of the header keywords against predefined following steps that are carried out by the rules;through the ESO archive. They form a PI/CoI and the ESO staff working in the — the FTP server (phase3ftp.eso.org)simple hierarchical structure where the External Data Products (EDP) group. PI/ that is used in the Phase 3 process byPhase 3 programme is at the top, fol­ CoI activities include the definition of new the PI/CoI.lowed by data collection and data data collections and releases, data prep­releases at the bottom. A data release aration and validation, data upload to the On the ESO side, the release managermust be associated to one, and only ESO staging area, creation and upload of is accessed in “operator mode” at theone, data collection. The hierarchy of the the release description, and finally closing beginning of the Phase 3 process, to cre­Phase 3 concepts is illustrated in Fig­ the release. The PI of an ESO programme ate a new Phase 3 programme, and ature 2. The data collection allows the data can delegate the Phase 3 process to one the end, after the data products pass thefrom a given programme to be organised or more people to distribute the effort of science validation, for their ingestionaccording to high-level criteria into self- data submission and release preparation. into the ESO archive. Applying for theconsistent groups, which the archive user Multiple delegates can, in principle, work automatic ingestion of the data productsthen can browse and access. on the same data release but it is the sole ex tracts the header information and responsibility of the PI to finally ensure loads this information into the ESO meta­As an example of the application of these the overall consistency. data repository, while all data files areconcepts, a Phase 3 programme is then sent to the bulk storage system in theone of the survey projects (e.g., VHS), On the ESO side, the EDP’s activities ESO archive. Two independent copiesone data collection of which may corre­ are to create the Phase 3 programme, of all the data are kept for reasons ofspond to one target object, or a target validate the submitted data, then carry safety. A summary showing the differentregion in case of a survey (e.g., the South out their archival and publication. The interfaces of the Phase 3 infrastructureGalactic Pole for the VHS survey). The validation of the submitted data includes with users and the archive facility is dis­collection name must be defined when the automatic validation of the data played in Figure 4.starting data submission and cannot be against the published format standardsrevised at a later stage by the user. Each for data products, including their header An important aspect of the support pro­data release must also be supported by keywords, as a first step, and the verifi- vided by the EDP group is the monitor-a release description that specifies con­ cation of the data release content as a ing of the submitted data products withtent, data properties and form. second step. During scientific validation, respect to the executed observations. To the completeness and consistency of this end a dedicated application is used,The individual data release may be the data release description with respect which accesses the metadata repositoryconsidered to be a version of the data to the submitted products is examined and allows the association between datacollection. Subsequent data releasesfor the same collection may follow the Figure 3. Schematic Data Data diagram illustrating theinitial release to add more data accord­ Data User’s data release transfer to preparation validation Phase 3 process anding to the progress of the observing pro­ definition ESO responsibilities. P.I.gramme (e.g., Release 2, 3, etc.). The Data providerPhase 3 infrastructure allows the data “Closing” theprovider to complement, update or data releasesupersede a previous release accordingto the PI’s strategy for data publication. Data Archival Verification Automatic by EDP data release publication storage scientist validation18 The Messenger 144 – June 2011
  • sees that the first IDPs to be ingested and accessible by the community will be Data Validation, those generated by the most advanced Ingestion process pipelines. These IDPs will be made avail­ Staging area P.I. Web interface EDP able via the query interfaces in the sci­ Release Manager ence archive domain dedicated to data products. Phase 3 in operation Mass storage The Phase 3 tools were developed by the Archive Query engine Archive Query Metadata Archive users, interfaces researchers repository Data Flow Infrastructure Department, Catalogue and the operational deployment was car­ database ried out by the Operations Technical Support Department within ESO. The pro­ ESO Archive ject manager for the Phase 3 Infrastruc­ ture is Remco Slijkhuis, in collaboration VO client IVOA with the EDP group. Data Access Protocols ESO community Inputs from public survey users were collected during a dedicated one­dayFigure 4. Diagram illustrating the Phase 3 data flow engaged in further developing the Phase workshop on VISTA data products atand intefaces with users and the ESO Science 3 infrastructure so as to be able to accept ESO on 30 November 2010. The presen­Archive Facility. The staging area provides 15 TB ofdisk space. catalogues and internal data products tation of the Phase 3 infrastructure and (IDPs). tutorials were followed by a joint dis-product files and the successfully cussion with the VISTA survey teams,executed OBs at the survey telescopes Catalogues and whenever possible, the requests bystored in the Phase 2 database. As high-level data products, the resulting PIs for extra functionality were imple­ source catalogues from the public sur- mented in the Phase 3 infrastructure that vey projects represent particularly impor­ was deployed on 10 March 2011.Data standards tant results. They are delivered at the milestones set by the major survey The current Phase 3 submission forThe definition of data standards and releases, the first of which is on 1 Octo­ the VISTA public surveys is ongoing withthe deployment of the rules as the basis ber 2011, a year and a half after the 6.8 terabytes of data products cur-of the automatic validation are key beginning of science operation with rently uploaded on the Phase 3 stagingresponsibilities of the EDP group. Data VISTA. Source catalogues require the area. Once the scientific validation isstandards are required to characterise data from different bands and tiles to be completed by the EDP group, these datathe level of data reduction and calibra­ merged and a global calibration across products will be safely stored, and thention, to track provenance, which allows tiles to be applied. The catalogues are become available for community accessESO to monitor survey progress, and different from the source lists, which are via the archive query interfaces.finally to support the query for specific per-tile products and can be down-data products and VO protocols via the loaded as entire FITS tables. The cata­ For enquiries on the Phase 3 process orESO archive interfaces. logue contents will be searchable via to initiate a Phase 3 submission, please a dedicated query interface in the ESO contact usd-help@eso.org, quoting Sub­For the VISTA data, a number of product archive. Basic functionalities will be ject: Phase 3.types were identified: tiles, pawprints, supported to allow the archive user tostripe images, weight maps and source carry out searches by position as well aslists. Their definition and relevant key­ by non-positional source parameters Referenceswords are illustrated on the Phase 3 web­ for sources in any areas of the southern Arnaboldi, M. et al. 2007, The Messenger, 127, 28page1. sky, for further scientific selection and Capaccioli, M., Mancini, D. & Sedmak, G. 2005, investigation on the user’s computer. The Messenger, 120, 10 Emerson, J., McPherson, A. & Sutherland, W. 2006, The Messenger, 126, 41What’s next? Publication of catalogues IDPsand internal data products An important aspect of the Phase 3 con­ cepts is that they were developed to LinksWhile supporting the Phase 3 process support the publication of the data prod­ 1 Phase 3 web information: http://www.eso.org/sci/for ESO programmes and developing ucts generated by ESO as part of the observing/phase3.htmlnew data standards, the EDP group is quality control process. The DPD fore­ The Messenger 144 – June 2011 19
  • Astronomical Science Colour-composite image of the nearby Carina dwarf spheroidal galaxy formed from the combination of thousands of images in U, B, V and I with many telescopes and imagers including the MPG/ESO 2.2-metre telescope and Wide Field Imager. See the article by Stetson et al. (p. 32) for more details.
  • Astronomical ScienceA VISIR Mid-infrared Imaging Survey of Post-AGB StarsEric Lagadec1 phase to the planetary nebula (PN) stage. cumstellar material in either a dusty torusTijl Verhoelst 2 As they ascend the AGB, their mass-loss or a disc. Our team has discovered someDjamel Mekarnia 3 rate increases from solar-like values of discs/tori in the heart of PNe (LagadecOlga Suarez 3, 4 10 –14 MA /yr up to 10 –4 MA /yr. The inte­ et al., 2006; Chesneau et al., 2006;Albert A. Zijlstra 5 grated mass lost from these stars is an Matsuura et al., 2006; Chesneau et al.,Philippe Bendjoya 3 essential component of galactic evolu­ 2007) using adaptive optics on ESO’sRyszard Szczerba 6 tion, as it is the main source of s-process Very Large Telescope (VLT) and mid-Olivier Chesneau 3 elements in the Universe and the main infrared (MIR) interferometry at the VeryHans Van Winckel2 producer of carbon. AGB stars are also Large Telescope Interferometer (VLTI).Michael J. Barlow7 the main contributors to the dust phase But the role of these discs/tori in theMikako Matsuura7, 8 of the interstellar medium (ISM). During shaping of the nebulae is still unclear, asJanet E. Bowey7 the last stages of AGB evolution, the we know neither the fraction of the totalSilvia Lorenz-Martins 9 remains of the convective hydrogen enve­ dust mass that is present in these cen-Tim Gledhill10 lope are ejected during final, quiescent tral cores, nor the fraction of objects and sporadic mass-loss events. Dust exhibiting such a disc/torus structure. grains and molecules, predominantly CO,1 ESO form in their winds, forming large circum­ In order to observe the inner region of2 Instituut voor Sterrenkunde, Katholieke stellar envelopes that can be detected post-AGB stars, we need MIR observa­ Universiteit Leuven, Belgium in the infrared and millimetre domains. tions, as the dust optical depth is smaller3 Fizeau, OCA /UNS/CNRS, Nice, France at longer wavelengths. The MIR is the only4 Instituto de Astrofisica de Andalucia, A departure from spherically symmetric wavelength range at which we can ob­ Granada, Spain mass­loss is observed in a substantial serve the inner morphology of stars from5 Jodrell Bank Centre for Astrophysics, fraction of suspected AGB to PN transi­ the AGB to the PPN phase. Furthermore, University of Manchester, United tion objects. In particular, multipolar the main source of radiation for these Kingdom structures are often associated with sources in the MIR is direct emission from6 N. Copernicus Astronomical Center, protoplanetary nebulae (PPNe). The dust, while at shorter wavelengths it is Torun, Poland three-dimensional morphologies of these scattered light. Mid-infrared imaging is7 University College London, United objects are projected on the sky, thus thus the best way to study the dusty Kingdom making it difficult to determine the structures inside these evolved stars.8 Mullard Space Science Laboratory, intrinsic morphology of PPNe and PNe. Univerisity College London, United But it is estimated that around 80 % Many MIR imaging observations of post- Kingdom of all PNe show aspherical morphologies. AGB stars have been made in the past.9 Universidade Federal do Rio de Hubble Space Telescope observations But the only available MIR imaging survey Janeiro, Brazil of PNe, for example, show a large range (Meixner et al., 1999) has been made10 University of Hertfordshire, United of morphologies, including elliptical, with 3-metre-class telescopes and suf­ Kingdom bipolar, multipolar or round nebulae. fers from limited angular resolution for the morphological study of the observed Hydrodynamical models explain many objects; in addition the survey selection isPost asymptotic giant branch (AGB) of the observed structures from a struc­ biased, as known bipolar nebulae werestars are key objects for the study ture-magnification mechanism, where observed. The survey consisted of onlyof the dramatic morphological changes a fast wind from the central star of the PN 17 resolved sources. Some work hasthat low- to intermediate-mass stars ploughs into the earlier slow AGB wind, been done using 8-metre-class tele­undergo during their evolution from the amplifying any density asymmetry already scopes, but always focusing on particularAGB towards the planetary nebula present: this is the generalised interact- individual bright, well-known objects.stage. There is growing evidence that ing stellar wind model (GISW). Anotherbinary interaction processes may play model has also been proposed to explain Here we present the results from the firsta determining role in shaping many the shaping of PNe. In this model shap- mid-infrared N­band imaging surveyobjects, but so far direct evidence for ing occurs at the end of the AGB phase, of a large number of post-AGB stars withbinarity is still weak. We report on a when fast collimated jets are triggered 8-metre-class telescopes. We aim at asystematic study of the dust distribution and shape a bipolar nebula. If the direc­ systematic survey probing the inner dustyaround a large sample of post-AGB tion of the jets changes with time, then regions of post-AGB stars.stars that probes the symmetry-break- multipolar nebulae can be formed.ing in the nebulae around these systems. Such jets could be formed through inter­ action with a companion, e.g., in an Target selection and observations accretion disc (see Balick & Frank [2002]According to our current understanding for a review). The large sample of observations cameof stellar evolution, all stars with main from five distinct observing runs fromsequence masses in the range 1–8 MA Much of the theory of the shaping of PN VISIR/VLT, Michelle/Gemini North andevolve via the asymptotic giant branch and PPN relies on the presence of cir­ T-Recs/Gemini South. The Messenger 144 – June 2011 21
  • Astronomical Science Lagadec E. et al., A VISIR Mid-infrared Imaging Survey of Post-AGB StarsOur sample contains the brightest post-AGB stars observable from Paranal and IRAS 10197 IRAS 16594includes PPNe, R CrB stars, RV Tauristars and “Water Fountains”. R CrB starsare hydrogen-deficient post-AGB starswith known obscuration events. RV Tauristars are pulsating post-AGB stars,located at the high luminosity end of thePopulation II Cepheid instability strip.These RV Tauri stars are likely to harbourcompact dusty discs. Water Fountainsare oxygen­rich PPNe characterised bythe presence of blue and red-shifted 1 1OH and H2O masers, hence their curiousclass name. Some bona fide PN andevolved massive stars were also IRAS 17311 IRAS 17441observed.Most of the observations were obtainedwith the MIR instrument VISIR on theVLT. The excellent observing conditionsduring our run (0.43 mm of precipitablewater vapour in the atmosphere), com­bined with the burst mode on VISIR,allowed us to obtain high quality diffrac­tion-limited images. The burst modereadout allows every single frame of anexposure to be saved. In this way it is 1 1possible to follow rapidly evolving eventsor to improve the spatial resolution by Figure 1. VISIR 10 μm images of a sample of post- close to the central star; the objects with AGB stars with resolved central cores. The desig-taking short enough exposures to freeze detached shells are characterised by nation of each target is given and the spatial scaleatmospheric turbulence, as in lucky is shown. the presence of a clear double-peakedimaging (e.g., Law et al., 2006). This mode distribution to the SED, with a first peakcan be used only for objects that are at a wavelength shorter than 1 μm duebright enough to provide a high enough For the largest objects that are clearly to the central star, and a second peaksignal-to-noise (S/N) in a single elemen­ resolved, we notice that the PPNe can due to the cool dust in the shell. The fluxtary frame. be divided into two categories. On the is much lower in the near­IR due to the one hand the objects with a dense cen­ absence of dust close to the central star.We thus observed 93 evolved stars in tral core, in the form of a bright central Figure 3 shows examples of both SEDs.a quasi-uniform way in the mid-infrared, source or a dark lane, with most of thewith a spatial resolution of the order of emission coming from the poles, indicate The very strong correlation between the0.3 arcseconds (which is the diffraction the presence of a large amount of dust, presence of a dense core and the bipo-limit at this wavelength). making the central regions optically thick lar morphology is an indication that the even in the MIR. Four examples are shown dense cores play a role in the shaping of in Figure 1. On the other hand, some ob- the nebulae. Two main classes of modelsTwo kinds of objects: resolved cores and jects do not have such a dominant cen­ have been proposed to explain the shap­detached shells tral core, and we can observe either a ing of nebulae. The first class of models detached shell or the central star (exam­ is based on the GISW models and hereFrom the set of 93 objects we observed, ples in Figure 2). The objects without a a fast wind from the central star of a PPN59 appear as point sources. Among the central core all have an elliptical morphol­ or PN interacts with a slower wind, aextended targets, we resolved a wealth ogy, while the objects with a central core remnant of the AGB phase, assumed toof different structures, such as resolved are either bipolar or multipolar. Both be toroidal. In the second class of mod­central cores, dark central lanes, de­ types of sources are differentiated in their els, the primary shaping agents are high-tached shells, S-shaped outflows. If we spectral energy distribution (SED): the speed collimated outflows or jets that areconsider only the PPNe from our sample, objects with a dense central core or an created at the end of the AGB phase orwe arrive at a sample of 52 detected equatorial dark lane have a rather flat at the beginning of the PPN phase. Theobjects. SED in the near-infrared wavelength interaction of these jets with a spherical range, due to the presence of hot dust AGB wind will create lobes that are in fact22 The Messenger 144 – June 2011
  • Most AGB stars have a large-scale circu­ IRAS 07134 IRAS 17163 larly symmetric morphology, while PNe display a variety of morphologies from elliptical to bipolar or multipolar. Optical imaging surveys of PNe indicate that 80 % of the PNe show a clear sign of departure from circular symmetry, and thus that approximately 20 % of PNe are spherical. The shaping of the PNe is thought to occur at the very end of the AGB phase or the beginning of the PPN phase. It is thus surprising that in our 1 1 sample of 25 resolved PPNe, we do not find any circular ones. IRAS 19374 IRAS 19500 The fact that we do not observe any circular PPNe could be a sample selec­ tion effect. We selected our targets as bright IRAS 12 μm sources. To be a bright emitter at these wavelengths, an object needs to have dust with a tem­ perature of approximately 300 K, which must therefore be located close to the central star. This is the case for the stars with a central core, which are aspheri- cal. The spherical PPNe are fainter than the non-spherical ones in the mid-infrared, 1 1 due to the lack of a central torus/disc emitting in this wavelength range. At theFigure 2. VISIR 10 μm images of a sample of post- end of the AGB phase, the envelopesAGB stars with detached shells. Annotations are as of the AGB progenitors of circular PPNein Figure 1. are ejected and rapidly cool down while expanding. There are thus very few IRAS 17441 IRAS 19500 Figure 3. Typical spec­ spherical PPNe that are bright in the mid- tral energy distributions 100.00 infrared. Furthermore those bright PPNe 100 of the two classes of objects observed. Left: are compact and thus difficult to spa- 10.00 an object with a dense tially resolve. The best way to detect such equatorial dusty torus spherical envelopes is thus at longer and a bipolar/multipolar wavelengths, and such detached shellsFlux (Jy) Flux (Jy) 10 1.00 morphology. Right: an object with a detached are actually observed in the far infrared shell and an elliptical with the Herschel Space Observatory. 0.10 morphology. 1 0.01 Formation of point-symmetric structures 1 10 100 1 10 100 Wavelength ( m) Wavelength ( m) A few objects that we resolved display a point-symmetric morphology, with an S-shaped envelope. One of our targets,cavities. If the direction of the jets Departure from circular symmetry IRAS 17441 (shown lower right in Fig­changes with time, multipolar nebulae ure 1), displays a tilt between the orienta­can be shaped. All the PPNe we resolved in our survey tion of the resolved central dusty torus show a clear departure from circular sym­ and the tips of the observed S-shapedBoth models require the presence of a metry. Some circular shells are resolved, structure. Such a tilt was observedcentral torus/disc in the core of the neb­ but only around massive evolved stars. by Volk et al. (2007), and measured toula. Our observations clearly indicate A dramatic change in the distribution of be almost 90 degrees. They suggestedthat the bipolar and multipolar nebulae the circumstellar material is often ob- that a precession of the dusty torusdo have such a central structure in their served when a star evolves from the AGB could explain the observed S-shapedcore. to the PN phase (Balick & Frank, 2002). structure of the nebula. They estimated The Messenger 144 – June 2011 23
  • Astronomical Science Lagadec E. et al., A VISIR Mid-infrared Imaging Survey of Post-AGB Starsthe dynamical age of the envelope, envelopes. For the oxygen-rich sources, evolution of low- and intermediate-massassuming a distance of 1 kpc and an we find that 10 out of 11 are bipolar stars. This dust is ejected into the ISMexpansion velocity of 100 km/s, to or multipolar, while the remaining one is during the PPN phase. Our observationsbe approximately 100 yr. According to elliptical. For the carbon-rich sources, show the existence of two paths forthis model, the torus should thus pre- we find that two are bipolar or multipolar this dust ejection, via a detached shell orcess with a rate of around 1°/yr. As our and two elliptical. The three objects an expanding torus. It is now becomingobservations were made four years after with a dual dust chemistry are multipolar clear that the bipolar objects with anthe observations presented by Volk et or bipolar. This is in agreement with the equatorial torus have been formed via theal. (2007), we should see a tilt of the torus recent work by Guzman-Ramirez et al. interaction with a binary companion.of about 4° between the two observa­ (2010), which shows a strong correlation This opens up a new field of research totions. The images provided by these between dual dust chemistry and the study the impact of the presence of aauthors show that the orientation of the presence of an equatorial overdensity. binary companion on the dust formationtorus that they observed is exactly the The dual dust chemistry could be due by evolved stars. In order to better under­same as the one we observed. The torus either to the formation of PAHs in an oxy­ stand the importance of PPNe for thein the core of IRAS 17441 is thus not pre­ gen-rich torus after CO photodissocia­ life cycle of dust, it would be interestingcessing at such a high rate. tion, or to the presence of a long-lived to study how these different paths affect oxygen-rich disc formed before the star the dust production by these objects.It appears that we cannot explain the turned carbon­rich due to the third Spatially resolved VISIR mid-infraredobserved S-shaped structures with a dredge-up. spectra of these sources will allow us toprecession of the central tori. This could study the dust composition at differentbe due to the fact that we underesti­ Stanghellini et al. (2007) also studied the locations in these PPNe, enabling usmated the dynamical age of the nebula or correlation between dust composition to better understand the evolution of dustthat another mechanism is responsible and morphologies. They determined, during the PPNe phase, from its forma­for the S-shaped structure. A more plau­ from a study of 41 Magellanic Cloud PNe, tion to its ejection, and how the presencesible explanation is that the S-shaped that all PNe with oxygen­rich dust are of a dense dusty disc affects its compo­structure is not due to the precession of bipolar or highly asymmetric. Our study sition.the torus itself, but to precessing out­ agrees with this finding, and it seemsflows inside this torus. The presence of that oxygen-rich PPNe appear to be Finally, the mass loss from evolved starssuch outflows has been observed in bipolar or multipolar. The low C/O ratio of is a key ingredient for our understand-the PN NGC 6302, which has a morphol­ these bipolar nebulae could be due to ing in many fields of astrophysics, includ­ogy very similar to that of IRAS 17441 the interaction with a binary companion ing stellar evolution and the enrichment(Meaburn et al., 2008). These outflows during a common envelope phase, or, in of the ISM via stellar yields. The aim of anare of a Hubble-type, which means that the case of single star evolution, result ongoing ESO large programme (PI: C.their velocity is proportional to the dis­ from conversion of carbon to nitrogen. Paladini), which will combine MIDI + VISIRtance from the source. A torus similar to The common envelope interaction will + Herschel observations of a sample ofthe ones observed in the core of these lead to the ejection of the envelope earlier evolved stars, is to constrain the geome­objects is also seen in the core of than in the single star evolution scenario, try of this mass loss at different spatialNGC 6302. The properties of such out­ leading to a less efficient dredge-up of scales. We will then be able to fully un-flows can be theoretically described carbon, and thus a lower C/O ratio. The derstand the dust evolution from its for­by a sudden ejection of material, a “bul­ conversion of carbon to nitrogen occurs mation in a circumstellar envelope until itslet”. Such bullets naturally account for for massive AGB stars in the hot bottom- injection into the ISM, and better under­multipolar flows, which could arise natu­ burning process. It is thus likely that the stand the life cycle of dust.rally from the fragmentation of an ex- bipolar PPNe have progenitors with largerplosively driven polar-directed shell. We masses than the elliptical ones. This ispostulate that the S-shaped structure in agreement with the work by Corradi & Referencesobserved in IRAS 17441 is due to high Schwartz (1995), who showed that bipo­ Balick, B. & Frank, A. 2002, ARA&A, 40, 439speed outflows triggered at the end of lar PNe tend to have a higher progenitor Chesneau, O. et al. 2006, A&A, 455, 1009the AGB phase, or the beginning of the mass. Soker (1998) proposed that this Chesneau, O. et al. 2007, A&A, 473, L29PPN phase, likely during an explosive result could be explained in the paradigm Corradi, R. L. M. & Schwarz, H. E. 1995, A&A, 293, 871event. of binary system progenitors, as prima­ Guzman-Ramirez, L. et al. 2011, MNRAS ries that undergo a common envelope Lagadec, E. et al. 2006, A&A, 448, 203 phase, and thus become bipolar, tend to Lagadec, E. et al. 2011, MNRAS, in pressChemistry and morphology have a higher mass. Law, N. M. et al. 2006, MNRAS, 368, 1917 Matsuura, M. et al. 2006, ApJl, 646, L123 Meaburn, J. et al., 2008, MNRAS, 385, 269Amongst the PPNe clearly resolved in our Meixner, M. et al. 1999, ApJS, 122, 221survey, 18 have known dust chemistry: Future directions Stanghellini, L. et al. 2007, ApJ, 671, 1669either oxygen­rich, carbon­rich or a dual Soker, N. 1998, ApJ, 496, 833dust chemistry with both carbonaceous A large fraction of the dust in galaxies isand oxygeneous dust grains in their produced during the late stages of the24 The Messenger 144 – June 2011
  • Astronomical ScienceThe VISTA Near-infrared YJKs Public Survey of theMagellanic Clouds System (VMC)Maria-Rosa Cioni1, 2 13 UK Astronomy Technology Centre, debate as to whether it is also of tidalGisella Clementini 3 United Kingdom origin from the interaction of the LargeLeo Girardi4 14 Centre for Astrophysics, University of Magellanic Cloud (LMC) with the SmallRoald Guandalini1 Central Lancshire, United Kingdom Magellanic Cloud (SMC), or produced byMarco Gullieuszik5 15 University of Cambridge, Institute of ram pressure between the two galaxies.Brent Miszalski1 Astronomy, United KingdomMaria-Ida Moretti 6 16 ESO The VMC1 survey is acquiring near-infra­Vincenzo Ripepi7 17 UPMC, University of Paris, Institut red (NIR) data of unprecedented sensi-Stefano Rubele 4 d’Astrophysique de Paris, France tivity in the Magellanic system that is ofGemma Bagheri1 18 CNRS, Institut d’Astrophysique de immense value for the astronomical com­Kenji Bekki 8 Paris, France munity. The survey represents the onlyNick Cross 9 19 LERMA, Observatoire de Paris, France NIR counterpart to existing optical sur­Erwin de Blok10 20 University of Zurich, Institute of Theo­ veys and for the large number of unclas­Richard de Grijs11 retical Physics, Switzerland sified objects observed with the SpitzerJim Emerson12 21 University of Exeter, School of Physics, Space Telescope in the mid-infrared. TheChris Evans13 United Kingdom VMC will cover the bulk of the MagellanicBrad Gibson14 22 University of Keele, School of Physical system as opposed to the tiny regionsEduardo Gonzales-Solares15 and Geographical Sciences, United sampled by the Hubble Space Telescope,Martin Groenewegen 5 Kingdom and the limited area covered by most ofMike Irwin15 23 University of Leicester, United King­ the other ground­based observations atValentin Ivanov16 dom the same sensitivity.Jim Lewis15 24 Mount Stromlo Observatory, RSSA,Marcella Marconi7 AustraliaJean-Baptiste Marquette17, 18Chiara Mastropietro19Ben Moore 20 The VISTA public survey project VMCRalf Napiwotzki1 targets the Large Magellanic Cloud,Tim Naylor21 the Small Magellanic Cloud, the BridgeJoana Oliveira 22 and two fields in the Stream. The VMCMike Read 9 survey is a uniform and homogeneousEckhard Sutorius 9 survey in the Y, J and Ks near-infraredJacco van Loon 22 filters. The main goals are the determi-Mark Wilkinson 23 nation of the star formation history andPeter Wood24 the three-dimensional structure of the Magellanic system. The survey is there- Figure 1. VMC logo fore designed to reach stars as faint1 University of Hertfordshire, Physics as the oldest main sequence turn-off Astronomy and Mathematics, United point and to constrain the mean magni- Current open questions about the for- Kingdom tude of pulsating variable stars such mation and evolution of the Magellanic2 University Observatory Munich, as RR Lyrae and Cepheids. We provide Clouds will be addressed by the VMC Germany a brief overview of the survey strategy survey, such as: How have the SFHs of3 INAF, Osservatorio Astronomico di and first science results. Further details the LMC and SMC been influenced by Bologna, Italy are given in Cioni et al. (2011). interaction? Does the geometry of the4 INAF, Osservatorio Astronomico di Magellanic system depend on age and Padova, Italy metallicity? Why is there a significant5 Royal Observatory of Belgium, Belgium Introduction difference in structure between the gas6 University of Bologna, Department of and stars in the SMC? Astronomy, Italy The Magellanic Clouds offer an excellent7 INAF, Osservatorio Astronomico di laboratory for near-field cosmology. They Capodimonte, Italy represent the closest prototype for stud­ Observations and data reduction8 ICRAR, University of Western Australia, ies of interacting galaxies and their low Australia metallicity and high gas content provide VISTA 2 (Emerson et al. 2006) is the larg­9 University of Edinburgh, Institute for information about galaxies at an early est wide-field NIR imaging telescope Astronomy, United Kingdom stage of evolution. The Magellanic Clouds designed to perform survey operations.10 University of Cape Town, South Africa have experienced an extended star for­ The performance during commissioning11 Peking University, Kavli Institute for mation history (SFH) and their dynamical is presented by Emerson et al. (2010), Astronomy and Astrophysics, China interaction may be responsible for the while science verification programmes12 Queen Mary, University of London, formation of the Magellanic Bridge. The are summarised in Arnaboldi et al. (2010). United Kingdom origin of the Magellanic Stream is under The Messenger 144 – June 2011 25
  • Astronomical Science Cioni M.-R.. et al., The VISTA Near-infrared YJKs Public SurveyThe VMC survey parameters are listed observed in the LMC. One field covers sky levels. Tile catalogues are producedin Table 1. VMC uses three filters, Y, J the famous 30 Doradus region, one field following the application of a nebulos-and Ks for the analysis of colour–colour corresponds to the South Ecliptic Pole ity filter in order to remove diffuse varyingdiagrams; the wider colour spacing in (SEP) region, there are a pair of fields background on scales of 3 arcsecondsY–Ks provides a good characterisation of located in the northern outer part of the or larger (Irwin 2010). The average VMCthe sub-giant branch population for LMC disc while the remaining two fields parameters from all single-tile imagesderiving the SFH. Monitoring of variable are located towards the Bridge. The are given in Table 3 where the magnitudesources is performed in the Ks­band, progress of the VMC survey observations limit is at 5σ. This set comprises ob-where variable stars obey a clear period– up to 4 March 2011 is provided in Table 2. servations obtained up to the end ofmagnitude relation. The VMC survey area November 2010 but does not distinguishis shown in Figure 2. It covers the area The VISTA raw images are reduced by between crowded and uncrowded fieldsto a limiting B magnitude of 25 mag arc­ the VISTA Data Flow System (VDFS) for which the VMC has different observ­sec –2 for both galaxies and encompasses pipeline at the Cambridge Astronomical ing requirements.the major features traced by the distribu­ Survey Unit (CASU3). Standard reduc-tion of stars and gas. tion steps are performed and quality con­ Astrometry is based on the positions of trol parameters are calculated for both the many 2MASS sources within eachHere we focus on observations obtained monitoring and evaluating observing con­ detector. The median astrometric root-during the dry-run period (November ditions retrospectively. A tile image is pro­ mean-square is 80 milliarcseconds (mas)2009–March 2010) when VISTA was duced by combining different pawprint and is dominated by uncertainties ontested and survey operations were still images adjusted for astrometric and pho­ 2MASS coordinates. Residual systematicbeing defined. Six VMC fields were tometric distortions as well as different distortions across the VISTA field of view are present at the 25 mas level. The pho­ tometric calibration relies on the observa­Table 1. VMC survey parameters. tion of stars from the 2MASS catalogue with magnitudes in the range 12–14 in allFilter Y J Ks Filter Y J Ks bands. The calibration in the Y­band isCentral λ (μm) 1.02 1.25 2.15 Exposure time per epoch (s) 800 800 750 possible where the extinction is not tooBandwidth (μm) 0.10 0.18 0.30 No. of epochs 3 3 12 high, i.e. EB–V < 1.5 (Hodgkin et al. 2009).DIT (s) 20 10 5 Total exposure time (s) 2400 2400 9 000 Figure 3 shows the behaviour of VISTANo. of DITs 4 8 15 Sensitivity per epoch (Vega) 21.3 20.8 18.9 photometric uncertainties in a VMC field.No. of exposures 1 1 1 S/N per epoch 5.7 5.9 2.9 Uncertainties are reduced by about 50 %Micro-stepping 1 1 1 Total sensitivity (Vega) 21.9 21.4 20.3 compared to those for individual tilesNo. of jitters 5 5 5 Total S/N 10 10 10 and will reduce further for deep tiles. APawprints in tile 6 6 6 Saturation (Vega) 12.9 12.7 11.4 morphological classification flag is alsoPixel size (arcsec) 0.339 0.339 0.339 Area (deg2) 184 184 184 included in the catalogue.System FWHM 0.51 0.51 0.51 No. of tiles 110 110 110 The data reduced by the VDFS pipeline are ingested into the VISTA ScienceDescription VMC LMC SMC Bridge Stream Table 2. VMC survey Archive4 (VSA). At present these data are progress up to 4 MarchNo. of tiles 110 68 27 13 2 reduced with the version 1.0 of the 2011. (Items in blue referNo. of epochs 1980 1224 486 234 36 to the complete survey.) pipeline and include all VMC data ob-No. of Y epochs 330 204 81 39 6 served until end of November 2011. AtNo. of J epochs 330 204 81 39 6 the VSA the data are archived to produceNo. of Ks epochs 1320 816 324 156 24 standardised data products: individualObserved Y epochs 59 37 8 8 6 passband frame association and sourceObserved J epochs 58.5 38.5 6.5 7.5 6 association to provide multi-colour, multi-Observed Ks epochs 98.5 75 5 4.5 14 epoch source lists; cross-associationsNo. of observed epochs 216 150.5 19.5 20 26 with external catalogues; and deeperCompletion in Y 17.9 % 18.1% 9.9 % 20.5 % 100 % stacking. The position and magnitude ofCompletion in J 17.7 % 18.9 % 8% 19.2 % 100 % each source in a given table refers to theCompletion in Ks 7.5 % 9.2 % 1.5 % 2.9 % 58.3 % astrometrically and photometrically cali­Total completion 10.9 % 12.3 % 4% 8.5 % 72.2 % brated measurements using the parame­ ters specified in the image headers. In addition the magnitude of the brightestFilter FWHM Ellipticity Zero-point Mag. Limit Table 3. VMC survey tile quality up to stars (Ks < 12 mag.) are recovered for sat­ 30 November 2010.Y 1.03 (0.14) 0.06 (0.01) 23.44 (0.10) 21.00 (0.49) uration effects (Irwin 2009). Figure 4J 1.01 (0.13) 0.06 (0.01) 23.68 (0.14) 20.55 (0.44) shows the Ks magnitude difference forKs 0.92 (0.10) 0.05 (0.01) 23.00 (0.19) 19.25 (0.30) stars in a VMC field compared to 2MASS before and after saturation correction.26 The Messenger 144 – June 2011
  • 5.5h 5h 4.5h 4h 3.5h 3h 2.5h 2h 1.5h 1h – 58° STR EAM – 56° – 60° – 58° – 62°δ (J2 000) – 60° – 64° – 62° – 66° – 64° – 68° 7.5h 7h 6.5h 6h 5.5h 5h 4.5h 4h 3.5h 3h 2.5h 2h 1.5h 1h 0.5h 0h 23.5h 23h 22.5h α (J2 000)Figure 2. (Top) Magellanic system area tiled for VMC Figure 3. (Bottom left) Photometric uncertainties in Figure 4. (Bottom right) Magnitude difference forobservations superimposed on the distribution of the VMC data for stacked pawprints (dashed, dotted stars in common between VMC and 2MASS beforeH i gas (McClure-Griffiths et al. 2009). Tiles are col­ and continuous lines in the Ks-, J- and Y­bands (bottom) and after (middle) recovering the magnitudeour coded as follows: purple: completed; cyan: respectively) and tiles (red, green and blue circles in of VMC stars approaching the saturation limit; theobservations in progress; green: to be observed. the Ks-, J- and Y-bands respectively) in one field are adjustment applied is shown at top. shown. 2 K S CORR –K S CORR 15 VMC 10 0 5 NO 0 –2 200 13 14 15 16 2 σmag (10 – 3 mag) CORR K S –K S 0 2M –2 KS 100 J 2 K S –K S CORR Y NO 0 2M –2 0 14 16 18 20 10 12 14 mag KS The Messenger 144 – June 2011 27
  • Astronomical Science Cioni M.-R.. et al., The VISTA Near-infrared YJKs Public Survey Figure 5. Complete- the red giant branch (RGB) beginning at 1 ness results for the ~ 2 mag below the red clump, the South Ecliptic Pole 0.8 (SEP) field are shown for approximately circular region described 0.6 single epoch (in green) by the highest concentration of stars. 0.4 and deep stacked The RGB continues beyond the red images (in red). clump at brighter magnitudes describing 0.2 Y-band a narrow structure bending to red col­ 0 ours. The abrupt change in source den­ 1 sity at the tip of the RGB marks theCompleteness 0.8 transition to brighter asymptotic giant 0.6 branch (AGB) stars. The broad vertical 0.4 distribution of stars below the RGB is 0.2 J-band populated by Milky Way (MW) stars that 0 are easily distinguished from LMC stars. Cepheid and supergiant stars occupy the 1 region of the diagram to the bright and 0.8 blue side of the RGB, while RR Lyrae 0.6 stars are somewhat fainter than the red 0.4 clump and lie more or less parallel to the 0.2 sub-giant branch. KS-band 0 14 16 18 20 22 24 MAG The Ant diagram 12 10 10 Figure 7 shows the observed colour- colour diagram, and the corresponding 14 CMDs, of the VMC data in the SEP field. The distribution of sources in the colour– 16 colour diagram resembles the body of an 15 15 ant, with different parts distinguished:Y KS KS 18 – Gaster (–0.1 < (Y–J) < 0.3 and –0.3 < (J–Ks) < 0.3), shown in red, the lower 20 part of the ant body corresponds to 20 20 the location of MS stars in the LMC, 22 with the youngest being at the bluest extremity. – 0.5 0 0.5 1 0 1 0 1 2 – Mesosoma (0.2 < (Y–J) < 0.4 and Y–J J– KS Y – KS 0.4 < (J–Ks) < 0.75), shown in blue, the middle part of the ant body corresponds Figure 6. Colour–magnitude diagrams of VMC added and recovered stars. The results to the main locus of helium-burning sources in the SEP field. of this process are shown in Figure 5. giants in the LMC. Most of them are in the red clump. The completeness of the stellar photome­ – Petiole (0.15 < (Y–J) < 0.3 and 0.3 <  try as a function of location across the Colour–magnitude diagrams (J–Ks) < 0.4), shown in green, is a small Magellanic sytem and position in the col­ thin extension of the mesosoma at its our–magnitude diagrams is estimated via Figure 6 shows the colour–magnitude dia­ red side, and is mainly caused by fore­ the usual procedure of adding artificial grams (CMDs) of VMC stellar and proba­ ground bright stars in the MW stars of known magnitudes and positions ble stellar sources in the SEP field. These – Head (0.4 < (Y–J) < 0.55 and 0.65 <  to the images, then comparing them in data were extracted from the VSA. The (J–Ks) < 0.85), shown in magenta. Its the derived photometric catalogues. For exposure times per band correspond to main blob is defined by foreground this work tile images are created and 2400 s in Y, 2800 s in J and 9400 s in Ks. low-mass stars in the Milky Way. regions equivalent to 1/12 of the area are – Upper antenna (0.42 < (Y–J) < 0.6 and selected for performing PSF photometry. The distribution of stars in the CMDs 0.85 < (J–Ks) < 1.1), shown in cyan, Then, artificial stars are added randomly shows different stellar populations. The being formed by the more luminous at a mutual distance of > 30 pixels, so bluest conic structure, bending to red RGB stars in the LMC close to the tip of as not to increase the typical crowding of colours at bright magnitudes, is formed the RGB, extending up to (J–Ks) = 1 mag. the images. Artificial stars spanning by main sequence (MS) stars of increas­ – Lower antenna ((Y–J) > 0.55 and smaller bins are later grouped together to ing mass with increasing brightness. 0.6 < (J–Ks) < 0.85), shown in yellow, estimate the number ratio between The MS joins, via the sub-giant branch, corresponding to the (Y–J) redward 28 The Messenger 144 – June 2011
  • 4.5 1.5 Ant diagram 1.5 Ant diagram Upper antenna 4 Upper antenna Lower antenna 1 1 Lower antenna 3.5 Head Log(g) 3 J–KsJ – KS 0.5 0.5 Head Mesosoma Mesosoma Petiole 2.5 Petiole Gaster 0 0 2 Gaster – 0.5 – 0.5 1.5 – 0.4 – 0.2 0 0.2 0.4 0.6 0.8 1 1.2 1.4 0 0.5 1 Y–J Y–J 10 12 4.5 12 4 14 14 3.5 16 3 Ks Log(g)Y 16 18 2.5 18 2 20 20 1.5 22 22 0 1 2 0 0.5 1 1.5 2 2.5 Y – Ks Y–KsFigure 7. Colour–colour (“Ant diagrams”) and colour– The simulated Ant diagram is also shown the K-band that is only weakly af fectedmagnitude (CM) diagrams of VMC sources in the in Figure 7, where colours now represent by evolutionary effects, the spread in stel­SEP field are shown for observed magnitudes (upperand lower left) and simulated magnitudes (upper and the stellar surface gravity. lar mass within the instability strip andlower right). In the observed magnitude plots (left uncertainties in reddening corrections.column), the coloured points correspond to the mor­ Similarly, the Cepheid period–luminosityphological selection outlined in the text and labelled RR Lyrae stars and Cepheids relation in the K­band is much narrowerin the upper plot. The mapping of stellar surfacegravity to the simulated colour–colour and CM dia­ than the corresponding optical relations,grams is shown in the right column. Radially pulsating stars obey a period- and less affected by systematic uncer­ mean density relation that forms the tainties in reddening and metal content. basis of their use as standard candles to measure the distance to the host sys­ In the context of the VMC survey, the Ks extension of foreground low-mass stars tem. In particular, RR Lyrae stars obey photometry is taken in time series mode in the MW. a period–luminosity–metallicity relation in in order to obtain mean Ks magnitudes The Messenger 144 – June 2011 29
  • Astronomical Science Cioni M.-R.. et al., The VISTA Near-infrared YJKs Public Survey P = 0.601586 d; Epoch = 52581.80256 JD P = 3.87046 d; Epoch = 51566.70416 JD Figure 8. BEROS and Ks VMC light- curves for an RR Lyrae star (left) and α = 90.32399 deg; δ = – 66.74809 deg α = 88.87615 deg; δ = – 66.09933 deg 17.5 15.0 a Cepheid (right) in the SEP field. B15574 B6 104 18.0 15.2 18.5 15.4Beros 19.0 Beros 15.6 19.5 15.8 20.0 16.0 –1.0 0.0 1.0 2.0 –1.0 0.0 1.0 2.0 17.0 13.8 K15574 K6 104 17.5 14.0Ks Ks 18.0 14.2 18.5 14.4 –1.0 0.0 1.0 2.0 –1.0 0.0 1.0 2.0 Phase Phase Figure 9. Colour-composite image of LMC PN MG 60 made from single (left) and stacked (right) exposures in Y (blue), J (green) and Ks (red) pass­ bands.for RR Lyrae stars and Cepheids over the are 117 RR Lyrae and 21 Cepheids in shallower observations (shown in green),whole Magellanic system. Their period– common between EROS-2 and VMC. confirming the soundness of our observ­luminosity relations will be used to meas­ EROS-2 periodicities were confirmed by ing strategy, and allowing us to deriveure distances and construct a 3D map analysing their BEROS light­curves with mean magnitudes without using templateof the stellar distribution. The identifica­ GRATIS (Clementini et al. 2000). Figure 8 light-curves. The average of individualtion, period and epoch of maximum light shows BEROS and VMC light-curves of the Ks measures corresponds to 18.02 +/–for these objects are taken from micro­ RR Lyrae star #15574 (P = 0.601586 0.12 mag. and 14.17 +/– 0.06 mag. for thelensing surveys (EROS, MACHO and days) and the Cepheid variable #6104 RR Lyrae star and Cepheid, respectively.OGLE) of the LMC and SMC while in the (P = 3.87046 days). For the RR Lyrae starBridge we plan to use the VST data there is one point per night and thethemselves (Cappellaro, 2005). magnitude is the weighted average of all Planetary nebulae available observations, while for theThe location of the SEP field at the Cepheid two points, corresponding each Planetary Nebulae (PNe) are well knownperiphery of the LMC overlaps with to a different detector, are shown. Both for their role in the development of theEROS-2 (Tisserand et al., 2007). There light-curves are well sampled, including extragalactic standard candle planetary30 The Messenger 144 – June 2011
  • 11 13 15KS 17 19 21 – 0.5 0.0 0.5 1.0 1.5 2.0 J–KSFigure 10. Colour-composite image (2 by 2 arc­minutes, shown right) and CMD (shown left) of thestellar cluster KMHK 1577. The isochrone corre­sponds to an age of 0.63 Gyr and a metallicity ofZ = 0.004.nebula luminosity function (PNLF). Dis­ mainly misclassified field stars, compact and 9400 s in Ks; triangles indicate stellartances can be measured from the near- H ii regions or long-period variables. The sources and asterisks extended objects.universal bright end cut-off across all gal­ strongest emission lines in the NIR foraxy types, but it remains difficult to PNe include: H i at 1.083 μm in Y­band,explain how old stellar populations that Pa β in J, while Ks contains Br γ, multiple Acknowledgementslack recent star formation episodes could H i and molecular H2 lines. Figure 9 The VMC survey is supported by ESO and the UKproduce progenitors massive enough shows the impact of stacking individual STFC. This research has made use of Aladin,to power the high star luminosities popu­ VMC exposures to detect PNe. EROS-2 and 2MASS data. The UK’s VISTA Datalating the bright end. Flow System comprising the VISTA pipeline at CASU and the VISTA Science Archive at the Wide Field Astronomy Unit (WFAU) in Edinburgh has been cru­Magellanic Cloud PNe are well positioned Stellar clusters cial in providing us with calibrated data products forto further advance our understanding of this paper.the PNLF. The deep NIR photometry pro­ Stellar clusters are among the primaryvided by the VMC survey will allow new targets of the VMC survey. The detection ReferencesPNe to be detected and the enhanced of known stellar clusters will be exam-sensitivity to dust resulting from observa­ ined and new clusters will be searched Arnaboldi, M. et al. 2010, The Messenger, 134, 42tion in the NIR will enable identification for. The analysis of stellar clusters will Cappellaro, E. 2005, The Messenger, 120, 13 Cioni, M.-R. L. et al. 2011, A&A, 527, A116of contaminating compact H ii regions be centred on CMDs to estimate their Clementini, G. et al. 2000, AJ, 120, 2054and symbiotic stars. The synoptic nature ages and metallicities as well as on the Emerson, J. et al. 2006, The Messenger, 126, 41of the VMC survey, which allows varia- comparison with results obtained from Emerson, J. et al. 2010, The Messenger, 139, 2bility to be measured, will enable identifi­ optical surveys. Ages, masses and metal­ Hodgkin, S. T. et al. 2009, MNRAS, 394, 675 Irwin, M. 2009, UKIRT Newsletter, 25, 15cation of pulsating Mira stars in the most licities of stellar clusters will allow us to Irwin, M. 2010, UKIRT Newsletter, 26, 14obscured symbiotic stars, thus support­ discuss the SFH of the Magellanic Clouds Kontizas, M. et al. 1990, A&A, 84, 527ing the cleaning of the PNe sample. and radial abundance gradients. McClure-Griffiths, N. et al. 2009, ApJS, 181, 398 Tisserand, P. et al. 2007, A&A, 469, 387Within the first six VMC tiles in the LMC, Here we show results obtained for clustera combination of optical imaging, OGLE KHMK 1577 (Kontizas et al. 1990) in the Linkslight-curves, the VMC NIR data and SEP field. The properties of this cluster 1SAGE mid-infrared observations, reveals are unknown and it was chosen because VMC survey: http://star.herts.ac.uk/~mcioni/vmc/ 2 VISual and Infrared Telescope for Astronomythat only ~ 50 % of the objects previously of its favourable location at the centre (VISTA): http://www.vista.ac.ukcatalogued as PNe appear to be genuine. of a pawprint. The image and CMD of the 3 CASU: http://casu.ast.cam.ac.uk/surveys-projects/These are characterised by the colours cluster are shown in Figure 10. The expo­ vista 40.4 < (J–Ks) < 2 and 0.0 < (Y–J) < 0.5. sure time was 2400 s in Y, 2800 s in J VISTA Science Archive (VSA): http://horus.roe. ac.uk/vsa/login.htmlThe non-PNe identified in the sample are The Messenger 144 – June 2011 31
  • Astronomical ScienceThe Carina Dwarf Spheroidal Galaxy: A Goldmine forCosmology and Stellar AstrophysicsPeter B. Stetson1 support previous photometric evidence Carina plays a key role among the LGMatteo Monelli2, 3 that both the old (12 Gyr) and the inter- dSph galaxies for many reasons:Michele Fabrizio4 mediate-age (4–6 Gyr) subpopulations i) it is relatively close, and its centralAlistair Walker5 show a limited spread in chemical com- density is modest;Giuseppe Bono4, 6, 7 position. The use of the Carina galaxy ii) it shows multiple star formation epi­Roberto Buonanno4, 8 field as a possible standard stellar field sodes, separated in time and inFilippina Caputo 6 is outlined. the amount of stellar mass involvedSanti Cassisi 9 (Monelli et al., 2003);Carlo Corsi 6 iii) it hosts a broad variety of variableMassimo Dall’Ora10 Introduction stars ranging from low- and intermedi­Scilla Degl’Innocenti11, 12 ate-mass hydrogen-burning dwarfPatrick François13 Dwarf galaxies play a fundamental role Cepheids to low- and intermediate-Ivan Ferraro 6 in several astrophysical problems. Current mass helium-burning stars (AnomalousRoberto Gilmozzi7 cosmological simulations predict dwarf Cepheids; Dall’Ora et al., 2003);Giacinto Iannicola 6 satellite populations significantly larger iv) high resolution spectra are availableThibault Merle14 than the number of dwarfs observed near for fewer than a dozen bright red giantsMario Nonino15 giant spirals like the Milky Way and M31. (RGs). The mean metallicity is [Fe/H] =Adriano Pietrinferni 9 This discrepancy is known as the missing –1.69 with a spread of 0.5 (Koch et al.,Pier Prada Moroni11, 12 satellite problem and challenges the 2008);Luigi Pulone 6 current most popular cosmological model: v) calcium triplet measurements basedMartino Romaniello7 the Lambda Cold Dark Matter paradigm on medium resolution spectra are alsoFrederic Thévenin14 (Madau et al., 2008). However, it is not available for a large sample (437) of yet known whether this discrepancy is RG stars (Koch et al., 2006) with a due to limitations in the theoretical mod­ peak at [Fe/H] = –1.72, but ranges from1 DAO/HIA/NRC, Victoria, Canada elling or to observational bias at the – 2.5 to – 0.5. Using the same spectra,2 IAC, Tenerife, Spain faint end of the galaxy luminosity function but different selection criteria, Helmi3 Univ. La Laguna, Tenerife, Spain (Kravtsov, 2010). et al. (2006) found a metallicity distri­4 Univ. Tor Vergata, Roma, Italy bution from about – 2.3 to –1.3.5 NOAO/CTIO, La Serena, Chile The distribution of dwarf galaxies in6 INAF–OAR, Monte Porzio Catone, Italy multi-dimensional parameter space indi­ However, we are facing a stark discrep­7 ESO cates that they follow very tight relations. ancy between the spread in metallicity8 ASDC. Frascati, Italy In particular, Prada & Burkert (2002) suggested by spectroscopic measure­9 INAF–OACTe, Teramo, Italy suggested that Local Group (LG) dwarf ments and photometric metallicity indica­10 INAF–OAC, Napoli, Italy galaxies show strong correlations (Fun­ tors. Deep and accurate colour–magni­11 Univ. Pisa, Pisa, Italy damental Line [FL]) between mass-to- tude diagrams (CMDs) of Carina indicate12 INFN, Pisa, Italy light (M/L) ratio, surface brightness and that the width in colour of the red giant13 Obs. de Paris-Meudon, Paris, France metallicity (Z). They explained the corre- branch (RGB) is quite limited (Monelli14 Obs. Côte d’Azur, Nice, France lation between M/L ratio and Z using a et al., 2003; Harbeck et al., 2001). This15 INAF–OAT, Trieste, Italy simple chemical enrichment model where evidence was further supported in a the hot metal­enriched gas, at the end recent investigation by Bono et al. (2010) of the star formation epoch, is lost via employing a large number of multibandWe present deep and precise multiband galactic winds (Mac Low & Ferrara, 1999; (U, B, V, I) CCD images from ground-(U, B, V, I) optical data for the Carina Woo et al., 2008). Furthermore, the FL of based telescopes covering the entiredwarf spheroidal galaxy. Data were col- dwarf irregulars (dIs) in a five-dimensional body of the galaxy.lected using three different ground- parameter space (total mass, surfacebased telescopes (4-metre Blanco brightness, rotation velocity, metallicityCTIO, MPG/ESO 2.2-metre, 1.5-metre and star formation rate) is linear and tight, Photometric datasets and photometricCTIO) and cover the entire body of and extends the scaling relations of calibrationthe galaxy. We discuss the reliability of giant late-type galaxies to lower mass.the absolute photometric zero-point On the other hand, the FL of dwarf sphe­ The data were collected in variouscalibrations of images collected with roidals (dSphs) in a four-dimensional observing runs between December 1992large-format and mosaic CCD cameras. parameter space (total mass, surface and January 2005. They include imagesThe typical precision for the B- , V- brightness, rotation velocity and Z) is also from three telescopes: the Cerro Tololoand I-bands is better than 0.01 mag. linear and very tight, but is not an ex tra­ Inter-American Observatory (CTIO)The U-band is a little worse. A prelimi- polation of the scaling relations of giant 1.5-metre telescope with a single Tektro­nary comparison with scaled-solar early-type galaxies. nix 2K CCD, the CTIO 4-metre Blancoand α-enhanced evolutionary predic- telescope with the Mosaic ii camera, andtions covering a broad range of ages the MPG/ESO 2.2-metre telescope withand chemical compositions seems to the Wide Field Imager (WFI) camera (both32 The Messenger 144 – June 2011
  • proprietary and archival data). The data nificant part of his career attempting to repeatability of the observations. For ourdiscussed here represent 4152 individual ensure that measurements of very faint measurements we were able to imposeCCD images with essentially complete stars obtained with CCDs on large tele­ the additional condition that each starcoverage of the central regions of Carina scopes are on the same photometric shows no evidence of intrinsic variation at(about 40 by 55 arcminutes, lacking only system as measurements of very bright a level greater than 0.05 mag root meanthose regions obliterated by bright fore­ stars made with photomultipliers on small square (rms), when the data from all filtersground stars). They were obtained in four telescopes (Stetson, 2000; 2005)1. are considered.photometric bands (B and I with the1.5-metre telescope, and UBVI with both The question of whether the photometry The left panels of Figure 1 show the mag­the 4-metre and 2.2-metre telescopes). discussed here is on the standard system nitude residuals (in the sense publishedThe resulting colour image is shown on breaks down into two parts: minus ours) plotted versus apparentp. 20. i) the extent to which the CCD photome­ visual magnitude, while the right panels try, in general, is on the standard sys­ of Figure 1 plot the same residualsThe photometric data were reduced tem; and against the B–I colour. The differencesusing the DAOPHOT/ALLFRAME package ii) the extent to which the photometry for show a systematic departure of a few(Stetson, 1987; 1994). Because of the Carina, in particular, is on the same hundredths of a magnitude between ourmultiple chips and pointings, any given system as the rest of the photometry. photometric system and the standardstar may have up to 17 calibrated meas­ As of now, 2076 datasets have been system for stars brighter than approxi­urements in U, 156 in B, 207 in V, and homogeneously analysed through our mately V = 9. We infer that the stars with70 in I. A total of 205 338 individual stars software; among these, 1591 are V ≤ 9 were simply too bright to be meas­were catalogued and measured. Among considered to be of photometric qual­ ured with our equipment, and we werethese, 72 595 have photometric measure­ ity, and 485 have been analysed in unduly optimistic about these measure­ments in all four filters, while 129 230 non-photometric mode (viz. data taken ments. We therefore advise readers tohave at least V and either B–V or V–I. The under non-photometric conditions). ignore Stetson’s results for standard starsremainder, either extremely faint (i.e., with V ≤ 9 and rely entirely upon thedetectable in only one filter) or located Figure 1 shows the magnitude differ­ previously published photometric indicesnear the periphery, have astrometry and ences between the calibrated standard­ of such stars instead. Figure 1 demon­instrumental magnitudes only. system magnitudes from our own ob- strates that our photometry matches the servations of the fundamental photometric definitive published results with a highThe fundamental standard system of standards, as compared to the pub- degree of fidelity over a dynamic range ofphotometric magnitudes was established lished values for the same stars. In order ~ 600 in flux (9 < V < 16) and over the ~ ~decades ago using photoelectric pho­ to restrict the comparison to stars full available range of stellar temperature.tometers on small telescopes — mostly with the most reliable data, we consider Quantitatively, the weighted mean dif-of apertures 0.4–0.9 metres (e.g., Land­ only magnitudes based on at least five ferences between the published resultsolt, 1973; 1988; 1992; Graham, 1982; and independent measurements obtained on and ours are + 0.0012 ± 0.0028, + 0.0016references therein to the establishment photometric occasions, and having ± 0.0013, − 0.0007 ± 0.0009 and − 0.0025of UBV by Johnson and RI by Cousins). standard errors of the mean not greater ± 0.0013 mag in U, B, V and I, respec­One of the authors (PBS) has spent a sig­ than 0.02 mag based on the internal tively, based upon 109, 209, 220 and Figure 1. Left: From top 0.1 0.1 to bottom, difference in 0.0 0.0 U-, B-, V- and I­bands δUδU between standard sys­ – 0.1 – 0.1 tem magnitudes and the current observations 0.1 0.1 of the fundamental photometric standards 0.0 0.0 δBδB as a function of the vis­ – 0.1 – 0.1 ual magnitude. Right: Same as the left, but the difference in magnitude 0.1 0.1 is plotted as a function 0.0 0.0 δVδV of B–I. – 0.1 – 0.1 0.1 0.1 0.0 0.0 δIδI – 0.1 – 0.1 8 10 12 14 16 0.0 2.0 4.0 6.0 V B–I The Messenger 144 – June 2011 33
  • Astronomical Science Stetson P. et al., The Carina Dwarf Spheroidal Galaxy Figure 2. Left: Same as 0.1 0.1 the left panels of Figure 0.0 0.0 1, but the difference isδU δU between magnitudes – 0.1 – 0.1 based on datasets from nights when Carina was 0.1 0.1 observed (175 photo­ metric, 88 non-photo­ 0.0δB 0.0 δB metric) as compared – 0.1 – 0.1 to results from the rest of our nights — when Carina was not 0.1 0.1 observed (1416 clear, 0.0δV 0.0 397 cloudy) — for those δV – 0.1 – 0.1 stars in all our other fields that appear in both datasets. See text 0.1 0.1 for more details. Right: 0.0 0.0 Same as left, but differ­δI δI ence in magnitude is – 0.1 – 0.1 plotted as a function of B–I. 8 10 12 14 16 18 20 22 24 0.0 2.0 4.0 V B–I151 stars. Expressed as a standard devi­ our CCD data except in the U filter. In this tude differences are + 0.0010, – 0.0002,ation, the average standard residual of filter only, 451 stars common to the two – 0.0001 mag in B, V and I, respectively,one star is 0.027, 0.017, 0.012, 0.012 and samples — all of which lie in only one based on 8795, 14 945, and 10 329 stars.0.016 mag in U, B, V, R and I. It does field, Selected Area 98 — show a sys­ The formal statistical confidence intervalsnot seem that these numbers can be tematic offset of 0.036 mag. on these numbers are all < 1 × 10 –4 mag,reduced by obtaining more observations; but these are certainly underestimated;rather, they represent a fundamental The Johnson U bandpass has always we still need to think harder about how tolimit to the reliability with which any given been a little problematic. Its classical characterise our actual systematic un­individual star can be referred to a fun- implementation provided a bandpass certainties, given that so few independentdamental standard system, due to the defined by filter throughput on the long points of comparison are available to us.fact that even though stars may have the wavelength side, but by atmospheric However, the current evidence suggestssame broadband colours in one photo­ opacity on the short wavelength side. that systematic differences between ourmetric system, they can still have underly­ Furthermore, the atmospheric extinction Carina observations and the system ofing spectral energy distributions that in the U-band is very high: ~ 0.5 mag Landolt and Graham in B, V and I proba­differ in detail, and that will be sampled per airmass on good nights at 2000 bly do not greatly exceed a few timesdifferently by other filter sets. metres on mountaintops like Cerro Tololo 0.001 mag, and calibration issues will not or La Silla. Finally, this bandpass con- be a significant limiting factor for ourFigure 2 provides the same sort of com­ tains the Balmer convergence and jump interpretations so long as we use U onlyparison for all stars in all fields in the in hot stars, and a multitude of strong for differential comparisons within ourCarina observations (263 in number: 175 metal lines (including Ca ii H+K) and data.photometric, 88 non-photometric) as bands of molecules like CN in cool stars.compared to results for the same target All of these features make the U magni­stars appearing in our 1813 datasets tudes sensitive to the exact placement Comparison between theory andobtained on nights when Carina was not and shape of the instrumental bandpass. observationsobserved (1416 clear, 397 cloudy). Again We will continue to investigate the causewe have restricted the comparison to of this discrepancy, but for the present A detailed comparison between stellarstars with at least five photometric obser­ we expect that a correction of order one- populations in Carina with simple stellarvations, standard errors no larger than tenth to one-half the difference should populations belonging either to Galactic0.02 mag and no evidence of intrinsic be applied to our U-band results for globular clusters (GCs) or to intermediate-variation in excess of 0.05 mag rms when Carina to bring them closer to the stand­ age clusters in the Small Magellanicdata from all filters are considered. These ard system. Cloud was presented in Bono et al.new comparisons show a few signifi- (2010). The discrimination between fieldcant photometric outliers with magnitude The problem is that we do not have and Carina stars was performed usingdifferences > 0.10 mag, as expected in many other nights of southern hemi­ the U–V, B–I colour–colour plane. Fig­any large body of raw data, but the vast sphere observations that included meas­ ure 3 shows three different CMDs of themajority of stars show that the datasets urements in the U­band, to which we candidate Carina stars. Note that afterthat do include Carina observations are could compare. Quantitatively, apart from the selection there remain some fieldreasonably well matched to the rest of U, the formal weighted mean magni- stars with colours similar to Carina’s RGB34 The Messenger 144 – June 2011
  • (V ≤ 21.5, B–V ~ 0. 5 mag). The evolu- 16 Carina dSphtionary properties of low- and intermedi­ate-mass stars provide at least threeindependent metallicity indicators: theslope and the spread in colour of RGB 18stars; the spread in colour of red clump(RC) stars; and the spread in magnitudeof blue and red horizontal branch (HB)stars. Data plotted in this figure show thatboth RGB and RC stars cover a very lim­ 20 RC RGBited range in colour in the three adopted HB V (mag)CMDs. The same observation appliesto the spread in magnitude of blue andred HB stars. 22The theoretical framework for bothscaled­solar and α­enhanced evolu­ IntSGBtionary models is based on isochronesavailable in the BaSTI database(Pietrinferni et al., 2004; 2006). To com­ 24 OLdSGBpare theory and observations weadopted the distance modulus and the 0.0 0.5 1.0 1.5 0 1 2 3 0 1 2 3 4reddening available in the literature B–V (mag) B–I (mag) U–I (mag)(Dall’Ora et al., 2003; Monelli et al., 2003).As a first working hypothesis, we are Figure 3. Left: B–V, V colour–magnitude diagram of stellar tracers (SGB, HB). The red bars plotted at candidate Carina stars based on optical images the right display the intrinsic photometric error bothassuming that both the old and the inter­ collected with the MOSAIC camera at the 4-metre in magnitude and in colour. Middle: Same as left,mediate-age subpopulations have Blanco telescope, with the WFI at the MPG/ESO but candidate Carina stars are plotted in the B–I, Vscaled-solar chemical compositions. 2.2-metre telescope and with the 1.5-metre CTIO tel­ colour–magnitude diagram. Right: Same as left,Spectroscopic investigations indicate that escope. The blue labels mark intermediate-age but candidate Carina stars are plotted in the U–I, V stellar tracers (SGB, RC), while the red ones the old colour–magnitude diagram.α-elements in dSph galaxies may beoverabundant when compared with solarcomposition, but underabundant when isochrones is systematically larger than the old and the intermediate-age predic­compared with GCs of similar metallicity observed over the magnitude range tions attain colours that are similar to the(Tolstoy et al., 2009; and references of sub-giant branch (SGB) and RGB observed ones. In addition, we repeatedtherein). stars. The same outcome applies to the the comparison using isochrones assum­ intermediate-age (6 Gyr) subpopulation. ing different values of global metallicityThe left panels of Figure 4 show the com­ The current predictions with the most ([M/H], see labelled values). The rightparison in the V, B–V CMD, at fixed metal-poor composition attain colours panels of Figure 5 show the comparisonchemical composition ([Fe/H] = –1.79, that are similar to the red tail of RC stars. with isochrones of 12 Gyr (top) for the oldY = 0.245), with two old (top; 10, 12 Gyr) However, the observed CMDs show a and of 6 Gyr for the intermediate-ageand three intermediate-age (bottom; well defined separation between RC and sub-population.2, 4, 6 Gyr) isochrones. Data plotted in RGB stars.these panels display that theory and The key advantage in the approach weobservations, within the errors, agree To further constrain the impact of chemi­ adopted to compare theory and observa­quite well. The intermediate-age isochro­ cal composition on the evolutionary tions is that we are using theoretical pre­nes appear slightly bluer than the bulk properties of Carina stellar populations, dictions to constrain the relative differ­of the RGB stars, but the difference is of we assumed that both the old and the ence and the spread in the heavythe order of a few hundredths of a mag- intermediate-age sub-populations are element abundances of Carina subpopu­nitude. The right panels of Figure 4 show α-enhanced. The left panels of Figure 5 lations. The above findings indicate thatthe comparison at fixed age and different show the comparison with two old the possible abundance spreads of bothchemical compositions. In particular, (top; 10, 12 Gyr) and three intermediate- the old and the intermediate­age sub­the top right panel shows the comparison age (bottom; 2, 4, 6 Gyr) isochrones populations appear to be limited and ofwith three old isochrones of 12 Gyr and constructed assuming the same iron the order of 0.2–0.3 dex (Bono et al.,iron abundances ranging from –2.3 to content as the scaled­solar isochrones 2010; Fabrizio et al., 2011), thus support­–1.5 dex. Note that evolutionary models adopted in Figure 4, but an overabun­ ing the spread in iron abundances basedwere constructed assuming a helium­to­ dance of α-elements: [α/Fe] = 0.4. The on high resolution spectra provided bymetal enrichment ratio ΔY/ΔZ = 1.4 and a comparison between theory and obser­ Shetrone et al. (2003). Theoreticalmass­loss rate η = 0.4 (Pietrinferni et al., vation appears slightly better than for and empirical uncertainties do not allow2004). The colour range covered by the the scaled­solar isochrones, since both us to reach firm conclusions regarding The Messenger 144 – June 2011 35
  • Astronomical Science Stetson P. et al., The Carina Dwarf Spheroidal Galaxy 16 and the interplay between Big Bang [Fe/H] = –1.79 dex t = 12 Gyr nucleosynthesis and the creation of Y = 0.245 chemical elements in stars is one of the landmark achievements in astrophy- [Fe/H] = – 2.27 dex sics. The former largely relies on photom­ 10 Gyr [Fe/H] = –1.79 dex etry, the latter on spectroscopy. Many 18 12 Gyr [Fe/H] = –1.49 dex of the current open problems in stellar astrophysics are approached through a comparison between the theoretical and observational Hertzsprung–Russell 20 diagrams. This comparison relies onV (mag) three fundamental pillars: absolute dis­ tances, photometric calibrations, and input physics adopted in the stellar evolu­ tionary and pulsation models. 22 There is a threefold motivation for the ongoing effort for precise photometric calibrations for stellar populations in nearby dwarf galaxies: = 20.11 i) A systematic drift in photometric pre- 24 E(B – V ) = 0.03 cision when moving from bright to faint RG stars might produce a spread in 16 colour, and in turn, mimic a spread in metal content. Moreover, these sys­ t = 6 Gyr tems are characterised by very low stel­ lar densities, thus requiring that pho­ 2 Gyr tometry be collected with large format 18 4 Gyr and mosaic CCD cameras. Intense 6 Gyr effort to achieve consistent zero-points across the field is mandatory to avoid spurious broadening of the key evolu­ tionary sequences. ii) Dwarf galaxies in the Local Group and 20 in the local volume are often con-V (mag) taminated by foreground field stars. Their colours, unfortunately, are similar to the colours of Galactic RGs and main sequence (MS) stars, once again 22 mimicking a broadening in colour due to a spread in age and/or in metal­ licity. The separation of field and Galactic stars can be performed using radial velocity and/or proper motions, 24 but at present this approach is lim- ited to relatively bright RGs. A robust cleaning of MS and SG sequences can 0.0 0.5 1.0 1.5 0.0 0.5 1.0 1.5 be performed using colour–colour B–V (mag) B–V (mag) planes (Bono et al., 2010) and/or a sta­ tistical subtraction of a control fieldFigure 4. Left: B–V, V colour–magnitude diagram of the possible occurrence of an α­element (Balbinot et al., 2010). These ap-Carina based on optical images. The solid coloured enhancement. proaches require, once again, verylines display two old (top) and three intermediate-age(bottom) scaled-solar isochrones at fixed iron abun­ precise calibration in different bandsdance and different ages. The adopted true distance across multiple telescope pointings.modulus and the reddening are also indicated. Right: Future prospects iii) The use of variable stars as distanceSame as left panels, but comparison assumed an indicators, stellar tracers and phys-age of 12 Gyr for the old (top) and of 6 Gyr for theintermediate-age (bottom) subpopulation. The identification of the physical mecha­ ics laboratories requires precise nisms that drive the formation and time series data and multiband cali­ the evolution of stars and stellar systems, brations.36 The Messenger 144 – June 2011
  • 16 and in near-infrared (NIR) bands. All three [Fe/H] = –1.84 dex t = 12 Gyr Carina fields have 659 U-band, 5711 B­ [α/Fe] = +0.4 dex and V-band and 1467 I­band standard [M/H] = +0.4 dex stars spanning a region 123 by 149 arc­ [Fe/H] = – 2.14 dex minutes. The brightest standard has Y = 0.246 [Fe/H] = –1.84 dex V = 13.95; the median is V = 19.27; and 18 [Fe/H] = –1.62 dex the faintest V = 22.42 mag. The Carina 10 Gyr region together with other regions1 is thus a potential standard stellar field to cali­ 12 Gyr brate the next generation of large CCD 20 cameras.V (mag) The use of accurate and deep NIR data, together with the present dataset, can play a crucial role in the identification of field and Carina candidate stars using 22 optical–NIR colour–colour planes. The stronger sensitivity to effective tempera­ ture of the optical–NIR colours can also provide a robust separation between = 20.11 old and intermediate-age stars. At the 24 E(B – V ) = 0.03 same time, a high­resolution, high signal­ to-noise ratio spectroscopic study of 16 a sizable sample of RG stars and He- burning (RC, HB) stars is mandatory to t = 6 Gyr measure the abundance spread, if any, in old and intermediate-age stellar popu­ 2 Gyr (M/H) = 1.79 dex lations. 18 4 Gyr (M/H) = 1.49 dex 6 Gyr (M/H) = 1.29 dex References Balbinot, E. et al. 2010, MNRAS, 404, 1625 Bono, G. et al. 2010, PASP, 122, 651 Dall’Ora, M. et al. 2003, AJ, 126, 197 20 Fabrizio, M. et al. 2011, PASP acceptedV (mag) Graham, J. A. 1982, PASP, 94, 244 Helmi, A. et al. 2006, ApJL, 651, L121 Koch, A. et al. 2006, AJ, 131, 895 Koch, A. et al. 2008, AJ, 135, 1580 Kravtsov, A. 2010, Advances in Astronomy, 2010, 22 Landolt, A. U. 1973, AJ, 78, 959 Landolt, A. U. 1983, AJ, 88, 439 Landolt, A. U. 1992, AJ, 104, 340 Mac Low, M. & Ferrara, A. 1999, ApJ, 513, 142 Madau, P. et al. 2008, ApJ, 679, 1260 Monelli, M. et al. 2003, AJ, 126, 218 Pietrinferni, A. et al. 2004, ApJ, 612, 168 24 Pietrinferni, A. et al. 2006, ApJ, 642, 797 Prada, F. & Burkert, A. 2002, ApJ, 564L, 73 Shetrone M. D., et al. 2003, AJ, 125, 684 Stetson, P. B. 1987, PASP, 99, 191 0.0 0.5 1.0 1.5 0.0 0.5 1.0 1.5 Stetson, P. B. 1994, PASP, 106, 250 B–V (mag) B–V (mag) Stetson, P. B. 2000, PASP, 112, 925 Stetson, P. B. 2005, PASP, 117, 563Figure 5. Left: Same as left panels of Figure 4, but The way to easily overcome the above Tolstoy, E., Hill, V. & Tosi, M. 2009, ARA&A, 47, 371comparison performed using isochrones con­ Woo, J., Courteau, S. & Dekel, A. 2008, MNRAS, problems is to have a sizable sample 390, 1453structed by assuming the same iron content([Fe/H] = –1.84 dex) of the scaled-solar models, but of local standard stars covering a broadwith an α-enhanced chemical composition (see range of magnitudes and colours.labelled values). Right: Same as left panels, but Local standards are now available in a Linkscomparison performed using isochrones with differ­ significant fraction of globular clusters. 1 List of photometric standard fields: http://www3.ent global metallicities ([M/H], see labelled values). So far, only a few dwarf galaxies have cadc-ccda.hia-iha.nrc-cnrc.gc.ca/community/ precise local standard stars in the optical STETSON/standards/ The Messenger 144 – June 2011 37
  • Astronomical News (Top) Workshop participants hard at work during the ALMA simulator tuto­ rial, see Randall & Testi, p. 39, for details. (Bottom) Photo of the partici­ pants at the worshop The Evolution of Compact Binaries, taken on the beach of Viňa del Mar. See Schmidtobreick & Schreiber, p. 47.
  • Astronomical NewsReport on the WorkshopALMA Community Days: Towards Early Scienceheld at ESO Headquarters, Garching, Germany, 6–7 April 2011Suzanna Randall1 frequency range from 30 GHz to 1 THz at capacity of 100 participants was easilyLeonardo Testi1 angular resolutions as high as 5 milli- reached (see Figure 1). The Community arcseconds. Dynamic scheduling and Days were followed by a dedicated work­ innovative calibration strategies will ensure shop on massive star formation with1 ESO the most efficient use of the unique the ALMA Early Science capabilities (see atmospheric qualities encountered at the Longmore et al. p. 41). Interestingly, 5000-metre-high site on the Chajnantor a large fraction (~ 40 %) of the workshopALMA is rapidly approaching Early Sci- plateau in the northern Chilean Andes. participants described themselves asence operations, and is scheduled novices in radio/sub-mm interferometry,to start the first observing projects for While Full Science operations are indicating that ALMA is eagerly awaitedthe astronomical community in the scheduled to begin in 2013, the increas­ not only by radio/sub-mm astronomers,autumn of 2011. The Call for Proposals ing capabilities of the growing array but also by the wider astronomical com­for ALMA Early Science Cycle 0 was will become available to the astronomical munity.published on 30 March, inviting the community following the start of Earlycommunity to submit observing pro- Science operations in the autumn of 2011.posals by the deadline of 30 June 2011. Early Science operations will be divided ALMA Early Science and commissioning/Held just after the Call for Proposals into two observing periods, Cycle 0 and science verificationwas issued, the ALMA Community Days Cycle 1, each planned to last betweenwere designed to optimally prepare nine and twelve months. It is expected The presentations on the first day werethe European ALMA Community for that the capabilities of the array offered kicked off by L. Testi, who reportedCycle 0 proposal submission. The work- to the community will substantially in­ on the current status of ALMA and theshop included a broad range of scien- crease from Cycle 0 to Cycle 1, and then capabilities offered during Early Science.tific and technical presentations as well again for Full Science operations. In Cycle 0, a minimum of 16 antennasas hands-on software tutorials for the will be working together in two configura­ALMA simulators and the Observing The aim of this two-day workshop was tions with baselines up to 125 metresTool. to optimally prepare the European astro­ and 400 metres. Four receiver bands will nomical community for ALMA Early Sci­ be offered, covering the frequency ranges ence. The first day was dedicated to 84–116 GHz (around 3 mm; Band 3),ALMA, the Atacama Large Millimeter/ a series of technical and scientific pres­ 211–275 GHz (around 1.3 mm; Band 6),submillimeter Array, is expected to be entations on the status of ALMA and the 275–373 GHz (around 850 μm; Band 7)the world’s leading observatory at milli­ capabilities offered in Early Science, and 602–720 GHz (around 450 μm;metre and submillimetre (sub-mm) while the second day was taken up by Band 9). One major limitation in Cycle 0wavelengths over the coming decades. hands­on tutorials on the two most is the time available for scientific obser-A global collaboration involving Europe, important pieces of software for ALMA vations: accepted programmes will beNorth America, East Asia as well as proposal preparation — the ALMA scheduled for up to one third of the timethe host country Chile, ALMA will com­ Observing Tool and the ALMA simulators.prise at least 66 high-precision anten- The ALMA Community Days were very Figure 1. The participants at the 2011 ALMAnas equipped with receiver and digital well received by the European astro- Community Days gathered outside the ESOelectronics systems to observe in the nomical community, and the maximum Headquarters. The Messenger 144 – June 2011 39
  • Astronomical News Randall S., Testi L., Report on the Workshop “ALMA Community Days”on a best-effort basis, while the comple­ base with answers to frequently asked of a self-calibration test, reveal a num-tion of the array is given priority. Single questions and allows registered users ber of molecular absorption and hydro­dish observations, polarisation measure­ to submit tickets that will receive a cus­ gen recombination lines and are alreadyments and solar observations are not tomised reply. comparable or superior in quality toyet offered, but are planned for Cycle 1. spectroscopy taken with existing facilities, The ALMA Science Portal gives access such as Owens Valley Radio Observa-The audience was given a first-hand to a suite of ALMA-related software. tory. ALMA will also be a powerful tool forimpression of the current commissioning During the first stages of proposal prepa­ studying asymptotic giant branch stars,and science verification activities at the ration, the ALMA simulators, introduced in particular their envelopes, as explainedALMA site in Chile by T. van Kempen and by E. van Kampen, can be used to by M. Maercker. Spectroscopy takenL. Humphreys. While some remarkable estimate the image fidelity achieved in a as part of commissioning on the evolvedcommissioning data had been obtained given observing time for the Cycle 0 star R Dor showed a far lower noisein the second half of 2010, progress array configurations. Similarly, the sensi­ level than equivalent data obtained with aslowed during the first quarter of 2011 tivity calculator can be used to estimate higher integration time with HIFI/Herschel.due to a particularly severe altiplanic win­ the integration time needed to achieve ALMA band 3 test data were also suc­ter and the deployment of a major soft­ a given sensitivity goal. Proposals must cessfully used to detect a detached shellware upgrade. However, the situation has be prepared and submitted with the around R Scl (see Figure 2).now improved, and the first science veri- ALMA Observing Tool (OT), which wasfication data (focussing on TW Hya and presented by A. Biggs. Finally, the data Extragalactic astrophysics and cosmol­NGC 3256) will be released to the public obtained in Cycle 0 will be reduced using ogy has always been one of the main sci­at the beginning of June. CASA scripts, while in the future an auto­ entific drivers behind ALMA. L. Cortese matic ALMA data reduction pipeline will showed beautiful commissioning data on become available, as outlined by D. Petry. NGC 253 (see the image in The Messen-The European ALMA Regional Centre ger 142, p. 17), which was observed in all the four bands that will be available inUser support for the European ALMA Science with ALMA Cycle 0. These data were used for con­community is handled by the European tinuum mapping at different wavelengthsALMA Regional Centre (ARC), which Observations obtained with ALMA are as well as velocity mapping from a num­currently consists of seven ARC nodes expected to have a significant impact on ber of the strong transition lines detected.distributed across Europe and a central a broad range of current research topics ALMA test data on extragalactic sourcescoordinating node hosted at ESO. The in astronomy. As convincingly demon­ also include NGC 3256, PKS 1830-211,European ARC, its staff and the services strated by A. Rushton, even Galactic BRI 0952, and the Cosmic Eyelash. In alloffered to the scientific community high-energy astrophysics, normally asso­ cases, the ALMA test data obtainedwere introduced by P. Andreani, while the ciated with much higher or lower fre­ with just 4–8 antennas are comparable orindividual nodes and the face-to-face quency observations, can benefit from superior in quality to those obtainedsupport offered there were presented by the unique capabilities of ALMA. ALMA with existing facilities, such as the Sub-M. Zwaan. An overview of the proposal test data for Sgr A*, obtained with five Millimeter Array (SMA) or the Plateaureview process was given by G. Mathys. antennas during commissioning as part de Bure Interferometer. The potential ofIn Cycle 0, it is expected that around100 proposals will be accepted, with an Figure 2. CO(1-0) test W. Vlemmings & M. Maercker. data of the detachedaverage execution time of 5–10 hours 15.0 shell around R Scleach. Projects not completed will not be observed with ALMAcarried over to Cycle 1, therefore the 20.0 with five antennas (redideal Cycle 0 project will produce imme­ contours). The grey- scale image shows stel­diately publishable results, highlighting the 25.0 lar light scattered byunique capabilities of Early Science ALMA dust particles in thewith only a few hours of observations. Declination – 32:32:30.0 detached shell observed with the ACS on HST (Olofsson et al., 2010).Comprehensive technical information 35.0on ALMA capabilities, proposal prepara­tion and relevant software is available 40.0online via the ALMA Science Portal1, aswas explained by F. Stoehr. Any techni- 45.0cal or scientific questions/commentsrelating to ALMA should be addressed to 50.0the ALMA Helpdesk, which was pre­sented by S. Randall. Accessible via the 59.5 59.0 58.5 1:26:58:0 57.5 57.0ALMA Science Portal, the Helpdesk con­ Right ascentiontains a regularly updated knowledge40 The Messenger 144 – June 2011
  • Astronomical NewsALMA for Solar System science was Hands-on software tutorials of excellent observing proposals andbriefly outlined by M. Zwaan. Since solar some spectacular scientific results duringobservations will not be offered in Cycle 0, The second and last day of the workshop Cycle 0 — and beyond!the current focus is expected to lie in was devoted entirely to hands-on soft­observations of the atmospheres of plan­ ware tutorials. Around 80 interested par­ The presentations and most of the tuto­ets and their moons, Kuiper Belt and ticipants were split into two groups rial material are available in electronictrans-Neptunian objects, and the study of depending on their previous experience form from the conference website:comets. Ironically, the only ALMA test in radio/sub-mm interferometry. Each http://www.eso.org/sci/meetings/2011/data currently available for a Solar Sys­ group was given a hands-on tutorial on alma_es_2011.html.tem body are single-dish observations of the two major pieces of software rele-the Sun taken during a period of par- vant to ALMA proposal preparation: theticularly bad weather, when the thick cloud OT and the ALMA simulators. While the Acknowledgementscover effectively acted as a solar filter! tutorials were held simultaneously for The organisation of the ALMA Community Days the two groups, those for the novice would not have been possible without the help ofStar formation, both at low- and high- users were slightly longer and included C. Stoffer, who took care of many of the practicalmass, is another research area that will an introduction to radio/sub-mm con­ aspects of the workshop and kept an overview at all times. We would also like to thank the members ofbenefit extensively from ALMA’s unique cepts (presented by A. Biggs) and inter­ the Organising Committee, S. Longmore, the entirecapabilities, as shown by J. Pineda and P. ferometry basics (given by A. Richards) ESO ARC staff and the ESO Garching IT HelpdeskKlaassen. ALMA band 7 test data have in the OT and the simulator sessions staff for their help. The tutorials on the second dayalready revealed outflows for a number of respectively. Both groups were given could not have taken place without the tutors: A. Biggs, A. Bridger, V. Casasola, B. Dabrowski, L.molecular species in NGC 1333 IRAS4B, software-specific presentations and live Humphreys, A. Kospal, S. Muller, S. Randall (OT) ;and the unprecedented sensitivity achiev­ demonstration sessions (with presenters A. Avison, A. Richards, A. Rushton, E. van Kampen,able even during Early Science is ex- A. Avison, A. Biggs, E. van Kampen M. Zwaan (Simulators). Finally, we would like to thankpected to have a strong impact on our and S. Randall), followed by a few hours all the speakers for putting so much work into their presentations. The workshop was sponsored byunderstanding of core formation, fragmen­ in which tutees could experiment with ESO and Radionet, which provided travel support totation, disc and planet formation, to give the software, with the help of a number a number of speakers and tutors.just a few examples. A 14.7 GHz wide of tutors (see upper figure on p. 38).band 7 spectral sweep of the Orion Klein­ Referencesmann–Low region, taken during ALMA The enthusiastic response of the Euro­commissioning as part of a spectral scan pean astronomical community to this Olofsson, H. et al. 2010, A&A, 515, 270test, impressively illustrates the potential workshop and the lively discussionsof ALMA for spectral line detection. With among the participants indicate that the Linksthe large bandwidth covered and the high groups specialising in the radio/sub-mm,sensitivity achieved, the ALMA test obser­ and other wavelength regimes, are 1 ALMA Science Portal: www.almascience.orgvations already entirely surpass SMA data eagerly awaiting ALMA and Early Science(see Figure 1 of Longmore et al. p. 42). operations. We look forward to a floodReport on theALMA Early Science Massive Star Formation Workshopheld at ESO Headquarters, Garching Germany, 8 April 2011Steven Longmore1 ing, a workshop was held for mem- interpret future ALMA data. The restLeonardo Testi1 bers of the European massive star for- of the meeting was spent discussingPamela Klaassen1 mation community to discuss ideas for science ideas and proposal strategies. potential ALMA Early Science projects. There was general agreement on the The workshop began with short sum- main science questions to be ad-1 ESO mary talks on the ALMA Early Science dressed, the basic observing strategies capabilities, the multi-wavelength large- required to achieve the goals and area survey data available as ALMA the future steps needed to develop theWith the deadline for ALMA Early Sci- source-finder charts and the modelling/ ideas into proposals.ence Cycle 0 proposals fast approach- analysis tools that are available to help The Messenger 144 – June 2011 41
  • Astronomical News Longmore S. et al., Report on “ALMA Early Science Massive Star Formation Workshop”With the deadline for ALMA Early Science potential ALMA Early Science projects. The workshop therefore began withCycle 0 proposals fast approaching1, a The workshop, which followed the ALMA review talks on the many single­dishdedicated workshop was organised, pro­ Community Days (see Randall et al. Galactic Plane surveys that have beenviding a forum for members of the Euro­ p. 39), was attended by 35 participants conducted over the past few years; thesepean massive star formation community from many institutions across Europe2 surveys will act as ALMA source-finderto get together and discuss ideas for (see Figure 2). charts. The advent of new facilities and instrumentation means that these surveys High-mass star formation is one of the are now available over most of the elec­Figure 1. Continuum-subtracted single polarisation key science topics that will exploit the tromagnetic spectrum, both in continuumuv-spectrum of Orion BN-KL. These observations order of magnitude improvements in sen­ from centimetre to near-infrared wave­consist of four frequency setups which have beenconcatenated together. With only five antennas, each sitivity, resolution, dynamic range and lengths (CORNISH3, BGPS4, ATLASGAL5,frequency setup was observed for 14 minutes, giv- image fidelity offered by ALMA over exist­ Hi-GAL6, HOBYS7, MIPSGAL8, GLIMPSE9,ing a total on source integration time of 56 minutes. ing millimetre and submillimetre interfer­ RMS10, UKIDSS11) and for spectral-lineThe lines identified at the Caltech Submillimeter ometers. ALMA will excel at providing emission (HOPS12, MA LT9013). The typicalObservatory by Schilke et al. (1997) are overplottedand labelled in red, except for transitions of CH3OH images in unprecedented detail and is angular resolution of these surveys range(green), HCOOCH3 (cyan), CH2CH3CN (yellow), the obvious follow-up instrument for from one to a few times the ALMA pri­CH3CH3CN (orange) and CH3OCH3 (magenta). lower-resolution, large-scale surveys. mary beam. This makes ALMA an ideal 13CH 3OH–A C 2H 5 3OCH 20 CH 3CH 2CN CH 3CH 2CN CH 3CH 2CN CH 3CH 2CN CH 2CHCN CH 2CHCN C 33 2CHCN SO 2(v2=1) SO 2(v2=1) SO 2(v2=1) CH33CH HC 3N(v7) NH 2COH NH 2COH NH 2CHO NH 2CHO NH 2CHO HCOOH HCOOH HCOOH HCOOH CH 3OH C 2H 5OH C 2H 5OH C 2H 5OH C 2H 5OH C 2H 5OH C 2H 5OH C 2H 5OH C 2H 5OH C 2H 5OH C 2H 5OH C 2H 5OH C 2H 5OH C 2H 5OH CH 25OH C 2H 5OH C 2H CO HC13O H 2CS 15 SiO OCS SO SO SO CHS SO 2 SO 2 SO 2 CN CN CN CN CN SO SOAmplitude 34 30 34 33 10 5 0 337.6 337.8 338 338.2 338.4 338.6 338.8 339 339.2 339.4 339.6 339.8 340 340.2 340.4 340.6 20 CH 3OCH 3 33–A CH 3OH–A HC 3OCH CH 3CHCN CH 3CHCN CH 3CHCN CH 3CHCN CH 3CHCN CH 3CHCN CH 3CHCN CH 3CHCN OH–E CH 3OCH 3 CH 3OCH 3 SO 2(v2=1) SO 2(v2=1) HC 2 CCN CH 3CCH CH 3CCH CH 3CCH CH 3CCH HCOOH HCOOH CH 2CO H 213CO OC 34S HC15N HCS + H 2CS H 2CS CS H 2CS H 2CS SO 2 SO 2 SO 2 15 SiO CH13 SO 3 SO 2 SO 2 SO CS 2Amplitude 34 34 33 34 29 13 10 5 0 341 341.5 342 342.5 343 343.5 344 H13CN(v2=1) 20 CH 3OH–A CH 3OH–A SO 2 3OH–E CH 3OH–E CH 2CHCN CH 2CHCN CH 2CHCN CH 2CHCN CH 2CHCN CH 3OCH 3 SO (v2=1) SO 2(v2=1) SO 2(v2=1) HC 3N(v7) HC 3N(v7) H13COu+ HCOOH C 2H 5OH SO 2CN SO 2u HC 3N SO 2 SO 2 SO 2 2 SO 2 SO 2 SO 2 33SO 2 SO 2 SO 2 SO 2 15 SO CH SO 2 2 SO 2 SO 2 SiO CO NS H13Amplitude 34 34 34 34 34 34 34 34 34 34 33 34 13 13 13 13 10 5 0 344.5 345 345.5 346 346.5 347 347.5 348 20 CH 3OH–A CH 3OH CH 3CN(v8) CH 3CN(v8) CH 3CN(v8) CH 3CN(v8) CH 3CN(v8) CH 3CN(v8) CH 3CN(v8) CH 3CN(v8) CH 3CN(v8) CH 3CN(v8) SO 2 CN(v8) CH 2CHCN CH 2CHCN CH 2CHCN CH 2CHCN CH OD–A NH3 CHO HCOOCH 3 CH 313CN CH 313CN CH 313CN CH 313CN C 2H 5OH CH 3CN CH 3CN CH 3CN CH 3CN CN CH 3CN CH 3CN CH 3CN CH 3CN CH 2CH 3CN HNCO HNCO HNCO HNCO H 2CS SO 2 SO 2 13 CH 313 SO 2 SO 3 15 CCH CCH CH 3CH 2CN 3 3 2 3 CH 3 3 2 SO 2 SO 2 NO NO CH 3OCH 3Amplitude 34 33 33 33 13 10 5 0 348.5 349 349.5 350 350.5 351 351.5 Frequency (GHz)42 The Messenger 144 – June 2011
  • instrument for exploring the structure Hans Zinneckerand physical properties of the compactsources found in the surveys. Indeed,the talks highlighted that several classesof sources that require such follow-up arealready being identified.Observations conducted during commis­sioning in 2010 already demonstrateALMA’s potential as a probe of the chem­ical structure of high-mass star forma-tion regions, thanks to the unprecedentedcombination of wide instantaneous band­width and sensitivity. Figure 1 shows aspectral sweep across part of the band 7(~ 345 GHz, 850 μm) window towards theOrion Becklin–Neugebauer Kleinmann–Low (BN-KL) high-mass star formationregion. Despite only 14 minutes on-source integration per frequency set-upand only five antennas, ALMA detectsa plethora of spectral-line emission fea­tures from a wide range of complex mol­ecules towards this hot core. This givessome idea of the complexity of the ALMAdatasets that can be expected from more Figure 2. Group photo of the workshop participants.distant and fainter high-mass star form-ing regions, as the number of ALMAantennas increases from 5 to 16 in Early unique objects chosen from the large- 7 HOBYS (Herschel imaging survey of OB Young Stellar objects): http://www.herschel.fr/cea/hobys/Science and finally to more than 50 in area surveys. The participants then split en/full operation. Given the expected com­ into smaller groups to further develop 8 MIPSGAL (Spitzer MIPS Galactic Plane survey):plexity of ALMA data, the workshop these ideas before reporting back to the http://mipsgal.ipac.caltech.edu/continued with a session discussing the full group on the outcome of their dis- 9 GLIMPSE (Galactic Legacy Infrared Mid-Plane Survey Extraordinaire): http://www.astro.wisc.various tools already available and cussions. In general there was agreement edu/sirtf/being developed (e.g., XCLASS14, LIME15, within the groups on the main science 10 RMS (Red MXS Source survey): http://www.ast.RADMC-3D16, MOLLIE17) that will be questions to be addressed, the basic leeds.ac.uk/RMS/necessary to analyse such datasets. observing strategies required to achieve 11 UKIDSS (UKIRT Infrared Deep Sky Survey): http:// www.ukidss.org/These tools are now maturing to a level the goals and the future steps needed to 12 HOPS (HMA LT90 (O southern Galactic Plane Sur­that will allow many future ALMA users develop the ideas. At the close of the vey): http://www.jcu.edu.au/school/mathphys/to perform detailed analysis of the data­ workshop, it was decided that each of astronomy/awalsh/HOPS/cubes. these groups would plan to continue and Walsh, A. et al, 2008, PASA, 25, 105 13 MALT90 (Millimetre Astronomy Legacy Team 90 these discussions in an ongoing build-up GHz Survey): http://malt90.bu.edu/The remainder of the workshop was to the proposal deadline. 14 XCLASS: http://www.astro.uni-koeln.de/projects/devoted to the presentation and discus­ schilke/XCLASSsion of science ideas and potential pro­ 15 LIME (LIne Modelling Engine): http://www.strw.lei­ Links denuniv.nl/~brinch/website/lime.htmlposal strategies. This began with sugges­ 16 RADMC-3D (Radiative transfer Monte Carlo 3D):tions on possible ways to organise the 1 ALMA Cycle 0 Call for Proposals: http://www. http://www.ita.uni-heidelberg.de/~dullemond/community to maximise the science out­ almascience.eso.org/call-for-proposals software/radmc-3d/put during ALMA Cycle 0. Some ideas 2 Workshop website: http://www.eso.org/sci/ 17 MOLLIE (MOLecular LIne Explorer): https://www. meetings/2011/alma_es_2011.html cfa.harvard.edu/~eketo/raised were: complementary frequency 3 CORNISH (COordinated Radio ‘N’ Infrared Surveyand line selection; co-ordinated propos­ for High-mass star formation): http://www.ast.als; and the relative merits of surveys and leeds.ac.uk/Cornish/public/index.phpsingle-object proposals. In the science 4 BGPS (Bolocam Northern Galactic Plane Survey):discussions that followed, several key http://milkyway.colorado.edu/bgps/ 5 ATLASGAL (APEX Telescope Large Area Surveyareas were highlighted which exploit the of the Galaxy): http://www.mpifr-bonn.mpg.de/unique ALMA Early Science capabilities div/atlasgal/and focus on well-selected samples or 6 Hi-GAL (Herschel Infrared Galactic Plane Survey): https://hi-gal.ifsi-roma.inaf.it/higal/ The Messenger 144 – June 2011 43
  • Astronomical NewsReport on the ESO WorkshopDynamics of Low-mass Stellar Systems: From Star Clustersto Dwarf Galaxiesheld at ESO Vitacura, Santiago, Chile, 4–8 April 2011Steffen Mieske1 Internal dynamics of compact stellarMark Gieles2 systems The meeting began with a full-day ses­1 ESO sion on the internal dynamics of compact2 Institute of Astronomy, Cambridge, stellar systems. The star cluster mass United Kingdom function and its evolution with time was the main topic of the morning session. Overview talks on this topic were deliv­The dynamics of low-mass stellar sys- ered by A. Jordan, B. Elmegreen, S.tems is not only an interesting subject Larsen and P. Goudfrooij. Clusters inin its own right, but is also intimately nearby galaxies form with a power-lawlinked to global theories of structure mass distribution, with indications forformation, the physics of gravity, and a truncation around a few 105 solarthe shape of the stellar initial mass masses (Larsen). The mass distributionfunction. Given the wealth of new infor- function of old clusters peaks (whenmation gathered very recently in this using logarithmic mass bins) at aroundfield, the time was ripe to hold a dedi- that mass (Jordan, Elmegreen). Despitecated meeting on this topic. The work- our long-established understanding ofshop brought together a mix of about the dynamical evolution of clusters, there100 astronomers who work on both the is still no consensus on whether the oldobservation and theory of the dynamics cluster mass function can be the resultof dwarf galaxies and star clusters, and of the (dynamical) evolution of a universala total of around 60 oral presentations Figure 1. Conference poster, showing ESO images power-law distribution, as observed at of Omega Centauri at the top left, and the dwarfand about 25 posters were presented. young ages in the present epoch. galaxy Sculptor at the bottom right. The red and blue curves show the radial behaviour of stellar velocity dispersions in these objects (from Scarpa & Fallomo, The mass-size relation (or lack thereof)At the low-mass end of stellar systems, 2010; Walker et al., 2009). The flat profile for the among star clusters was discussed by M. dwarf galaxy is typically interpreted as indicating thethere used to be a well-known dichotomy. Gieles, a topic that was brought up again presence of dark matter.On the one hand, there are star clusters several times during the meeting (seewith typical sizes of a few parsecs (pc), also Figure 3). Star cluster sizes seem towhose internal dynamics can generally The idea of our workshop, Dynamics of be uncorrelated with their masses up tobe well described by Newtonian gravity. Low-mass Stellar Systems: From Star a few million solar masses. Above this, inOn the other hand, there are the much Clusters to Dwarf Galaxies, was to dis­ the realm of UCDs, size increases withmore extended dwarf galaxies with sizes cuss the internal dynamics of these sys­ mass, joining an extrapolation of the rela­of several hundred pc, whose dynamics tems and their use as tracer particles in tion for giant galaxies. It was suggestedappear to be dark matter dominated large-scale potentials. Special emphasis that the lack of a mass-size relation ofand which are usually related to cosmo­ was placed on how the observed dy- clusters is the result of dynamical evolu­logical substructures (see Figure 1). These namics are linked to a more global con­ tion of star clusters away from a primor-classical boundaries have been blurred text of structure formation theories, in- dially existing relation. Subsequentlyby the recent discovery of new classes of cluding a discussion of the concordance the dynamical evolution of star clustersstellar groupings, such as ultra-faint cosmological model and possible alter­ under the influence of external tides (J.dwarf spheroidals, ultra-massive super natives. Another focus of this meeting Penarrubia & A.L. Vari) and internalstar clusters, ultra-compact dwarf gal- was the transition region between classi­axies (UCDs), and dark-matter-poor tidal cal star clusters and dwarf galaxies, in Figure 2. Conference photo taken in the garden ofdwarf galaxies (TDGs). particular UCDs. ESO’s Vitacura premises.44 The Messenger 144 – June 2011
  • 10 5 axies. It was concluded that most of the Local Group dwarfs have internal dy- Centaurus Es/dEs: Misgeld + 09 namics that are consistent with them Centaurus cE candidates: Misgeld + 09 being dark matter dominated, with some Hydra I Es/dEs: Misgeld + 08 ongoing debate on a few ultra-faint cE galaxies dwarfs. It was furthermore shown that 104 Coma cEs: Price + 09 TDGs may require a moderate amount of dark matter (baryonic or non-baryonic) LG dwarf galaxies to explain their internal dynamics. Pres­ entations by J. Bullock and M. Bovill drew attention to the problems of the con- cordance Lambda Cold Dark Matter 10 3 (ΛCDM) cosmological model in explain- ing the observed low frequency of bright satellites.R eff(pc) M32 Several presentations then focused on VUCD7 100 the dynamics of individual Local Group UCD3 dwarf spheroidals (S. Pasetto, S. Zaggia M59c0 & E. Lokas) including a comparison Es/dEs: Bender + 93 between Milky Way and M31 dwarf sphe­ bulges: Bender + 93 roidals (E. Tollerud). It appears that M31 ACSVCS galaxies: Ferrarese + 06 dwarfs have on average lower mass-to- 10 light (M/L) ratios at comparable luminosi­ Nuclear star clusters ACSVCS nuclei: Cote + 06 ties. It was stressed that stochastic fluc­ tuations may be a serious limiting factor ACSVCS GCs: Jordan + 09 in the predictive power of ΛCDM for indi­ UCDs: Mieske + 08, Misgeld + 11 vidual host halos such as the Milky Way Star clusters: Mclaughlin & v.d Marel 05 or M31. G. Mamon, M. Wilkinson and J. 1 Wolf discussed important aspects of 10 2 10 3 104 10 5 10 6 107 10 8 10 9 1010 1011 1012 1013 dynamical modelling of dwarf spheroidal stellar mass (M ) galaxies from a theoretical point of view. The afternoon talks were completed byFigure 3. Effective radius plotted vs. stellar mass for D.  Heggie, who showed that a proper a review by P. Kroupa of the problems ofall pressure-supported stellar systems (from Misgeld N-body simulation of a massive globular ΛCDM in the Local Group, proposing a& Hilker, 2011). This plot was repeatedly shown dur­ing the workshop and the dynamics of systems with cluster can(not?) be performed in a scenario where all dwarfs are formed asmasses below ~10 8 solar masses were discussed. human lifetime. The first day wrapped up TDGs without any dark matter. It wasDwarf galaxies are typically larger than 100 pc, while with talks on the observed internal dy­ shown that galaxy encounters can createstar clusters and UCDs are below that size. namics of nearby star clusters (A. Stolte counter­rotating tidal debris reminiscent & N. Bastian), and we learned that globu­ of today’s dwarf galaxies (M. Pawlowski).effects (R. Smith & L. Smith) were dis­ lar clusters (GCs) in Andromeda appear G. Hensler presented the chemo-cussed. to have dynamical masses that are too dynamical aspect of dwarf galaxy evolu­ low to be possibly explained by pro­ tion in a ΛCDM scenario.In the afternoon session, several talks nounced dynamical evolution (J. Strader).on the test of Modified Newtonian Dy- A “hot” discussion session led bynamics (MOND) with star cluster dynam­ M. Wilkinson concluded the secondics (R. Scarpa, R. Sollima & R. Lane) Internal dynamics of dwarf galaxies workshop day. The apparent problemswere presented. Those talks generated of ΛCDM in explaining the propertiesa very lively discussion on whether the The second day of the workshop was of Local Group galaxies for a range ofsuggested flattening of the dispersion dedicated to the dynamics of dwarf masses were debated. This includedprofile in the outskirts of some clusters is galaxies. The scene was set by review the missing-satellite problem that extendscaused by a breakdown of Newtonian presentations on the observed internal to higher masses than traditionally re­gravity, the influence of tidal fields, or dynamics of ultra-faint, classical and ported, and the disc of satellites, thecontamination. More work, especially in tidal dwarf galaxies by M. Geha, M. highly anisotropic distribution of Milkyterms of accurate dynamical model- Walker and P.-A. Duc, respectively. The Way dwarfs. At the same time, theling, will be needed to draw firm conclu­ influence of contaminators and binaries problems and failures of alternative ap-sions on this matter. The afternoon con­ on the derived velocity dispersions proaches like MOND to provide a fulltinued with a review of dynamic evolu­ was discussed; issues that are of special framework for explaining our observedtionary modelling of globular clusters by importance for the faintest dwarf gal- Universe were highlighted. The Messenger 144 – June 2011 45
  • Astronomical News Mieske S., Gieles M., Report on the Workshop “Dynamics of Low-mass Stellar Systems”Black holes in low­mass stellar systems dynamical tracers in the centres of star overview of structural and dynamical clusters. The third workshop day was properties of “hot” stellar systems overThe third day focused on black holes wrapped up by a dedicated poster ses­ ten orders of magnitude in mass (see Fig­in low­mass stellar systems, and whether sion with 20 short presentations. ure 3).star clusters extend the well­knownmass–sigma (M–σ) relation of giant galax­ies to lower masses. J. Anderson showed Star clusters as tracers in large scale The dwarf galaxy – star cluster interfacethat, from HST-based proper motion potentialsmeasurements, there is currently no evi­ The earlier presentations then set thedence for intermediate-mass black holes The fourth day of the workshop shifted scene for the last session of the fourthin the centres of massive Galactic star from the internal dynamics of low-mass day which was dedicated to UCDs — theclusters. This differed from the results of stellar systems to their use as tracers stellar systems at the interface betweenradial velocity studies via spectroscopy in large-scale host galaxy potentials. P. star clusters and dwarf galaxies. M.(presentations by N. Luetzgendorf, B. Coté reviewed the link between globular Hilker reviewed the general properties ofJahlali & E. Noyola; see Figure 4), which cluster subpopulations and their host UCDs. M. Frank presented fresh resultssuggest black holes of several tens of galaxy merger histories. This topic was on the spatially-resolved internal kinemat­thousands of solar masses in a couple of discussed further in presentations by ics of the most massive UCD (see Fig­Galactic star clusters. Direct compari- J. Brodie, R. Sanchez-Janssen and A. ure 5). He finds that its kinematics areson of proper motion and radial velocity Huxor. T. Richtler, A. Romanowsky and fully consistent with a “normal” star clus­data for Omega Centauri showed that the V. Pota gave an overview of how the kin­ ter, with no evidence for the presencediscrepancy can only partially be ex- ematics of globular cluster systems can of dark matter or a black hole. This wasplained by uncertainties in the adopted be used to constrain the dark matter halo considered an important step forwardcluster centre. H. Baumgardt reviewed shape of giant galaxies. The dynamical in our understanding of UCDs and theirthe dynamical evolution of star clusters in evolution of star clusters in an external origin. C. Bruens then showed N­bodythe presence of black holes. Finally, N. tidal field was discussed in presentations simulations, which suggested that UCDsNeumayer showed that several nuclear by A. Kuepper, D. Kruijssen, S. Bird may well be formed by the merging ofstar clusters contain a comparably mas­ and F. Renaud. I. Misgeld then gave an individual massive star clusters, and M.sive black hole. Whether or not star clus­ters follow the extrapolation of the M–σ ACS/HRC F606W Reconstructed Imagerelation to lower masses is still an openissue, and addressing this problem facessome fundamental limitations due to thefinite number of stars that can be used as K2 2 2 K1 N2 N1 N radius ( ) A1 A2 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 E 30 25 σ (Km/s –1) 30 20 25σ (Km/s) 20 constant M/L : red. X 2 = 1.13 15 M BH/M total= 5% : X 2 = 0.8, p = 37% 15 M BH/M total= 20% : X 2 = 4.3, p = 4% 10 M DM/M total(R < 200 pc) = 33% : X 2 = 1.3, p = 25% Kin center NGB08 center AvdM center 10 M DM/M total(R < 200 pc) = 60% : X 2 = 5.5, p = 2% 5 1 2 3 1 2 3 1 2 3 0 20 40 60 80 100 120 140 log(r) (arcsec) radius (pc)Figure 4. Kinematics of the centre of Omega Centauri Figure 5. Spatially resolved internal kinematicsmeasured with the FLAMES–ARGUS spectrograph at of Fornax UCD3 measured with the FLAMES–the VLT, as presented by E. Noyola at the workshop ARGUS spectrograph, as presented by M. Frank(Noyola et al., 2010). at the workshop (Frank et al., 2011).46 The Messenger 144 – June 2011
  • Astronomical NewsNorris discussed the ensemble proper­ of the nearby elliptical galaxy Centaurus of MOND does not provide by itself anties of UCDs in a statistical sense. A (NGC 5128). G. da Costa showed adequate description of the Universe as new results on the stellar dynamics in the a whole, lacking a cosmological frame­The fourth day concluded with a discus­ outskirts of Omega Centauri, arguing work. He argued that the internal dynam­sion session led by S. Mieske. It was that possible deviations from a Keplerian ics of Milky Way satellites within thenoted that the frequency of UCDs is con­ velocity dispersion profile are likely due radius of the Magellanic Stream are likelysistent with the hypothesis that they to tidal effects and/or interlopers. P. affected by tidal forces, and advocatedconstitute the bright tail of the globular Assmann and J. Hurley focused in their caution in the interpretation of dynamicalcluster luminosity function. UCDs can be talks on dwarf galaxy formation via star data of objects within that radius. Heexplained as massive star clusters, cluster mergers. The last session was added that objects in the transition regionwhose elevated M/L ratios are due to a rounded off by presentations on nuclear between galaxies and star clusters —non-canonical initial mass function. On and bright globular clusters in dwarf such as UCDs — can give fascinatingthe other hand, the formation of UCDs galaxies (I. Georgiev) and a discussion insights into galaxy transformation pro­via tidal stripping cannot be excluded as of cold halos and extended clusters in cesses and massive star cluster forma­an additional channel, given the obser­ M31 (M. Collins). tion, while constraints on dark mattervational evidence of tidal disruption of properties can only be obtained fromdwarf galaxies. Another topic of discus­ objects with sizes above ~100 pc, whichsion was whether star clusters would be Conference summary he considers as galaxies.expected to trace the M–σ relation to alower value of σ. It was concluded that An inspiring conference summary wasthis would strongly depend on the forma­ delivered by G. Gilmore. He made a Acknowledgementstion mechanism of putative massive black general point that the ΛCDM framework We warmly thank Maria Eugenia Gomez, Paulinaholes in them. provides a very good description of the Jiron, the team of ESO IT and General Services, and Universe from the largest scales down to the entire Local Organising Committee.The last day of the workshop was again galaxy size scales, and that, in particular,dedicated to the interface between star it describes the initial stages of the Uni­clusters and galaxies. D. Forbes dis­ verse very well. He also noted, however, References for figurescussed the definition of a galaxy, show- that there are considerable problems Frank, M. et al. 2011, MNRAS letters in press,ing that the presence of multiple stellar with ΛCDM predictions at smaller (galaxy) arXiv:1104.2593populations is considered the most defin­ scales. He argued that a possible avenue Misgeld, I. & Hilker, M. 2011, MNRAS in press,ing feature for a galaxy, according to towards a reconciliation of theory with arXiv:1103.1628 Noyola, E. et al. 2010, ApJ, 719L, 60an online poll amongst astronomers. the observed Universe at small scales Scarpa, R. & Fallomo, R. 2010, A&A 523, A43K. Woodley discussed the star cluster to may be less massive (= warm) dark mat­ Walker, M. et al. 2009, ApJ, 704, 1274UCD transition based on an extensive ter particles. He also made the point thatstudy of the globular cluster system in comparison with ΛCDM, the conceptReport on the WorkshopThe Evolution of Compact Binariesheld at Hotel San Martín, Viňa del Mar, Chile, 6–11 March 2011Linda Schmidtobreick1 with the aim of bringing together people urement and understanding of the brak-Matthias R. Schreiber2 from different communities to concen- ing mechanisms was the main discus- trate on the specific problem of binary sion point of the meeting. evolution. Compact binaries divide into1 ESO many classes, but the evolution of all2 Departamento de Física y Astronomía, these objects is driven by a common In order to bring astronomers from the Universidad de Valparaíso, Chile mechanism: angular momentum loss. different communities to an understand­ From the formation of compact binaries ing of the main problems in the evolution over the various phases of contact to of compact binaries, the workshop beganThe workshop, organised by ESO and their explosive deaths in a supernova with thorough introductory review talksthe Universidad de Valparaíso, was held Type Ia or gamma-ray burst, the meas- on the main types of compact binaries, The Messenger 144 – June 2011 47
  • Astronomical News Schmidtobreick L., Schreiber M., Report on the Workshop “The Evolution of Compact Binaries”like cataclysmic variables (by Ch. Knigge), evolution and no further evolutionary involved in binary evolution worked excel­low-mass X-ray binaries (P. Charles) assumptions are needed to link them to lently. In this format, the experts wereand high-mass X-ray binaries (S. Chaty). this phase. H. Boffin and D. Jones also present to answer any specific ques­Further general reviews were given by presented good evidence that binarity is tion that arose from the presentationsG. Hussain who thoroughly explained the responsible for the aspherical morphol­ and during the discussions. This helpedtheory and observations of the magnetic ogy of most nebulae and also explained to avoid fruitless speculations and tobraking mechanism in single stars and the details of the formation mechanisms. keep the discussions relevant to the sub­binaries, and by M. van der Sluys, who The subsequent discussions concen­ ject. On the other hand, since the par-introduced the concept of gravitational trated on the statistics of the observed ticipants came from different scientificradiation and the resultant braking effect. binaries with respect to the expectations communities, many unorthodox ideas from stellar population synthesis, and and suggestions came up and gave freshThe sessions themselves were organised the strong impact of the Sloan Digital Sky input to some discussion.following the evolution of compact bina­ Survey (SDSS) on this field became evi­ries in chronological order. The full pro­ dent. From the feedback that we got duringgramme of the meeting can be found on and after the workshop, it seems thatthe conference web page1. We started Cataclysmic variables, novae, symbiotic everyone had learnt something new, butwith close binary formation, which was stars and X-ray binaries in various fla­ was also able to contribute to the generalsummarised in a review by K. M. Kratter vours were discussed in the session on level of knowledge. Interaction betweenwho gave an overview on the different the contact phase. Since the evolution the participants was promoted not onlychannels to achieve a close binary con­ of any particular binary takes too long to by the space given in the individual ses­figuration and compared the theoretical observe, it is important to have homoge­ sions, but also by the various activitiespredictions with observational statistics neous samples, as was pointed out by taking place outside the conference roomon multiplicity. The contributed talks in several speakers. Surveys like SDSS or (see the lower figure on the Astronomicalthis session concentrated on multiplicity selections on X-rays or variability seem News section page, p. 38). The welcomeas observed in certain star-forming to be examples of ways to deal with this cocktail, a walk through the hills ofregions or in certain classes of stars and problem. The importance of metallicity Valparaíso, a boat trip in the harbour, theboth theory and observations agree that for binary evolution was stressed by F. conference dinner itself, and the closingmultiplicity increases strongly towards Mirabel and F. Valsecchi in their talks lunch helped to get people to talk tohigher stellar masses. about massive binaries and black holes. each other and thus to found new collab­ orations and friendships.If the binary components are sufficiently “Graveyard or Boom?” was the title ofclose, the evolving primary will at some the session about the final stages of bi- The proceedings of this workshop will bepoint fill its Roche lobe and thus start nary evolution and both possibilities were published in the Conference Series ofunstable mass transfer towards the sec­ introduced in the reviews: F. Röopke the Astronomical Society of the Pacific.ondary, resulting in a common envelope gave an overview on supernovae Type 1aphase. In her review, N. Ivanova intro­ and possible progenitors; T. Tauris intro­duced common envelope physics. Due duced binary pulsars; and E. Ramirez Linksto its short timescale, so far no direct explained gamma-ray bursts from the evo­ 1 Conference website: http://www.eso.org/sci/observations exist of this phase. There­ lutionary point of view. Many other con- meetings/Binary_Evolution2011/fore, the session was naturally domi- tributions dealt with the possible massnated by simulations and theoretical dis­ increase of white dwarfs in cataclysmiccussions on the impact that the com- variables, symbiotic stars or doublemon envelope has on the final binary degenerate binaries to thus reach theconfiguration. In particular, the efficiency Chandrasekhar limit and ignite the super­of the common envelope in bringing nova.stars together, and at the same timeexpelling the material of the envelope as The workshop ended with a short ses­a planetary nebula, seems to be finally sion on telescopes and instruments withunderstood, as was demonstrated by M. talks concerning the latest about theZorotovic. E-ELT, the possibilities of optical interfer­ ometry, and the young field of gravita­Planetary nebulae also played a major tional-wave astronomy.role in the contributions concernedwith the post common envelope phase. Intense and lively discussions took placeTogether with the hot subdwarfs, plane­ during the whole week of the workshop.tary nebulae represent the objects that The idea of having specialists givingarise directly out of common envelope the introductions to the specific physics48 The Messenger 144 – June 2011
  • Astronomical NewsESO Participates in Germany’s Girls’ Day ActivitiesDouglas Pierce-Price1 about the adventure of working at the audience informed and entertained in Very Large Telescope, and could appre­ equal measure, thanks to their lively and ciate the unfamiliar landscape of the engaging answers, and it was only lim­1 ESO Atacama Desert and the state-of-the-art ited time that prevented the discussion facilities on Cerro Paranal. This intro- lasting even longer. duction was followed by presentationsOn 14 April 2011, ESO took part in the on astronomy and the observatory sites, With this “visit” to ESO’s flagship site inGermany-wide Girls’ Day activities1, 2, in and on careers at ESO. Chile, the Girls’ Day came to an end.which technical enterprises, universities Thanks are due to all the staff membersand research organisations arranged After lunch, the students split into four who kindly volunteered to speak to theopen days for girls, to give female school groups, to visit different parts of ESO girls and show them around. We hopestudents an insight into scientific and Headquarters. They saw the activities in that the students will remember the expe­technological professions and to encour­ the optical and electronics laboratories, rience for a long time, and that it willage more of them to choose such careers and the work of the draughtspersons, as inspire some of them to pursue careers inin the future. well as having another chance to meet science and technology. They may even some of the astronomers and PhD stu­ enter the field of astronomy, in whichThe ESO Girls’ Day event, An Introduction dents at ESO. Throughout the tour they case perhaps we will have the chance toto the Work of the European Southern had the opportunity to ask many ques­ welcome them back to ESO in the future.Observatory, was organised by the tions about working at ESO.Human Resources department, with par­ticipation from volunteers across the Having seen the VLT in the morning’s film, Linksorganisation and support from the edu­ the students then had the next best 1 Girls’ Day in Germany: http://www.girls-day.de/cation and Public Outreach Department. experience to visiting it themselves: a live 2 English information about Girls’ Day in Germany:Spaces were soon fully booked, and video-link to both Paranal and the ESO http://www.girls-day.de/English_Informationabout 50 students attended the event at offices in Santiago, where astronomersESO Headquarters in Garching. The were available for a question-and-answergirls, aged between 11 and 16, came session. Seeing the mountaintop atfrom schools in Munich and the surround­ Paranal in real-time, with a giant VLT Uniting area. Telescope moving in the background, was a thrilling experience for the stu­In the morning, after being welcomed to dents. The volunteers at the other end ofESO, the students were shown a film the intercontinental video-link kept theAnnouncement of the ESO WorkshopTen Years of VLTI: From First Fringes to Core Science24–27 October 2011, ESO Headquarters, Garching, GermanyThe Very Large Telescope Interferometer user facility. At the VLTI, optical interfer­ the successful partnership between ESO(VLTI) saw first fringes in 2001 with a ometry has evolved from an initial experi­ and the international interferometricvery simple but powerful instrument mental phase, devoted mainly to tech- community. Turning the VLTI into a bonaknown as VINCI. Since then, the VLTI, nology demonstration, to the current fide common user facility has requiredwith the instruments AMBER and MIDI, phase where astronomers do not need to enormous efforts from scientists andhas become a major contributor to a be “black-belt” interferometrists to use engineers at ESO and in the community;number of important research domains in the instruments and extract valuable sci­ the close collaboration between ESO andcontemporary astrophysics, from the entific information about their favourite its user community was essential to thisnature of rocky objects in the Solar Sys­ targets. success.tem, to the nuclear regions of activegalaxies, in addition to detailed investiga­ There are three themes to the confer­ The second theme is to visit the sciencetions of stars and their close environ- ence. The first is to travel along the road that the VLTI will be doing in the era ofment. The VLTI is the first optical interfer­ of the VLTI over the last ten years, cele­ the Atacama Large Millimeter/submillime­ometer to be implemented as a common brating its scientific achievements and ter Array (ALMA) and the James Webb The Messenger 144 – June 2011 49
  • Astronomical NewsSpace Telescope (JWST). The VLTI is resolution. This conference will be an Further details are available at:evolving, and soon the first generation of opportunity to preview the science that http://www.eso.org/VLTI_2011/instruments will be followed by a new will be done by the ELTs and interfer-much more powerful suite. The trio of ometers together, and the technicalinstruments PRIMA, GRAVITY and requirements for the VLTI to enable thatMATISSE will offer much improved sensi­ science.tivity and imaging capabilities, charac-terising planets, stars and black holes at The Scientific Organising Committeeunprecedented levels of detail. These consists of: Olivier Absil (Liège), Robertoinstruments will arrive during a new era in Gilmozzi (ESO), Walter Jaffe (Leiden),observational astronomy: the Hubble Fabien Malbet (Grenoble), AlessandroSpace Telescope will be nearing the end Marconi (Florence), Jorge Melnick (ESO,of its mission; ALMA will have reached Chair), Antoine Mérand (ESO), Rafaelits full capability; and JWST will be get­ Millan-Gabet (Caltech), John Monnierting ready to launch. Together, ALMA, (Michigan), Jenny Patience (Exeter), GuyJWST and the VLTI will enable unprece­ Perrin (Paris Obs.), Didier Quelozdented advances in stellar physics and (Geneva), Gerd Weigelt (MPIfR Bonn) andthe nuclei of galaxies. Sebastian Wolf (Kiel).The third theme of the conference is to The Local Organising Committeeproject the VLTI beyond the second consists of: Francoise Delplancke (Chair),generation of instruments, at the time Roberto Gilmozzi, Christian Hummel,when the Extremely Large Telescopes Jorge Melnick, Isabelle Percheron,(ELTs) will begin to dominate ground- Gerard van Belle and Markus Wittkowski.based optical astronomy. The ELTs willhave unprecedented sensitivity while The registration deadline is 23 Septemberinterferometers will have superior spatial 2011.50 The Messenger 144 – June 2011
  • Astronomical NewsPersonnel MovementsArrivals (1 April–31 June 2011) Departures (1 April–31 June 2011)Europe EuropeMartis, Alessandro (IT) Contract Officer Di Dio, Tommaso (IT) AccountantVernazza, Pierre (FR) Fellow Kerk, Elizabeth (NL) HR OfficerGonzalez Villalba, Justo Antonio (ES) ALMA Data Analysis Swat, Arkadiusz (PL) Optical Engineer Software Developer Pomaroli, Edouard (FR) ElectromechanicIribarrem, Alvaro (BR) Student Slijkhuis, Remco (NL) Archival Data Product SpecialistZhao, Fei (CN) Student Bruton, Andrew (GB) Mechanical Technician Schleicher, Dominik (DE) FellowChile Fontani, Francesco (IT) Fellow Karovicova, Iva (CZ) StudentMawet, Dimitri (BE) Operations Astronomer Zabl, Johannes Florian (DE) StudentGaytan, Daniel (CL) Unix and Network Specialist Surdej, Isabelle (BE) StudentRiffo, Lidia (CL) SecretaryFoster-Guanzon, Caroline (CA) FellowAravena, Manuel (CL) Fellow ChileDel Valle, Diego (CL) Software Engineer Camuri, Massimiliano (IT) Electronic Engineer Orrego, Oscar (CL) Guesthouse SupervisorThis striking panoramic photo, taken by ESO Photo In the centre (above the VLT Auxilliary Telescope)Ambassador Yuri Beletsky, shows the sky over both the Magellanic Clouds can be seen and to theCerro Paranal during the total lunar eclipse of 21 left (east) the brightest source is the planet Venus,December 2010. The eclipsed moon (red disc) is vis­ adjacent to the zodiacal light. See Picture of theible just above the dome of VLT Unit Telescope 2. Week potw1119 for more details. The Messenger 144 – June 2011 51
  • Astronomical NewsFellows at ESOCiriaco Goddi and engineers/operators, the breath- taking night show of the Milky Way in theI grew up on a Mediterranean island, southern hemisphere, the majestic moun­the enchanting Sardinia (Italy), a place tains and the “martian” landscape ofwhere the low level of air and light pollu­ the Atacama desert, and the challenge oftion reveals a beautiful, dark, star-filled working in the rarefied atmosphere atnight sky (almost) all year long. I remem­ 5000 metres, just one step away from theber, as a child, being always fascinated sky! I ended up spending approximately(and overwhelmed) by the vastness of 80 nights observing in the Atacamathe Universe. My passion for scientific desert. APEX is one of the special obser­subjects and some books read during vatories in the world, and I will miss thehigh school (Weinberg and Hawking real family atmosphere (and the famouswere among my favourites) determined asados!).my choice: I wanted to be a physicist! Now, while entering the second half ofI undertook a path which began with my fellowship, for my functional work I willan undergraduate physics degree at the join the ALMA commissioning team, theUniversity of Cagliari in Sardinia. My biggest ground-based project in astron­Master’s thesis was on astronomy, where omy. I know that probably previousI analysed mid-infrared data from plane­ generations of astronomers, at differenttary nebulae taken with the SWS spec­ Ciriaco Goddi times, have said this already, but I trulytrometer on board the ISO satellite. Dur­ feel we are in a golden age for astronomy.ing my thesis work, I had the invaluable the analysis of a large dataset of radio New upcoming facilities like ALMA willopportunity to visit ESO as a summer interferometric data aimed at a detailed revolutionise our knowledge of the Uni­student. I had never been in a big insti­ study of an intriguing, yet enigmatic, verse and will bring great discoveries...tute at that time and I was overall so im­ region in the Orion Nebula. It is curious And I feel rather privileged to be part ofpressed by the scientific activity on that the favorite constellation of my child­ this revolution!campus, that once back at my home uni­ hood, The Hunter, turned out to beversity I decided to enroll in a PhD pro­ my “pet source” as a professional astron­gramme in astronomy. The main goal omer. We also developed websites and Petr Kabathof my PhD thesis project was to deter­ animations for public outreach, a valuablemine 3D gas dynamics in obscured mas­ way, in my view, to spread scientific My passion for astronomy started in highsive star-forming regions. I learned the knowledge among the general public. school almost two decades ago, lead­basics of radio interferometry, in particu­ ing me to study physics, and especiallylar very long baseline interferometry, I was awarded an ESO fellowship in astronomy, later. Currently, I am an ESOwhich, despite requiring labour-intensive 2009 and I moved back to Europe. ESO Chile fellow trying to contribute to andprocessing, allows images to be pro­ offers an incredibly stimulating scien- unveil some of the most intriguing scien­duced with the highest angular resolution tific atmosphere, with a remarkable diver­ tific topics of today, while working at thein astronomy. sity of research carried out by excellent world-leading Paranal Observatory. astronomers and a rich diet of work­After finishing my PhD in 2005, I spent shops, seminars, and lively discussions I was born in Brno, Czech Republic,one year at the INAF–Osservatorio Astro­ at morning coffee. As a co-organiser where I officially started my astronomyfisico di Arcetri in Florence, just next door of the weekly Informal Discussion, I have career at the local public observatoryto Galileo’s villa. There I joined the main had the opportunity to meet and interact in 1996. Years later, as my interest inresearch group on star formation in Italy, with many visiting (and ESO) astrono- astrophysics had steadily increased, Iwith whom I still collaborate today. mers and to learn about many aspects of enrolled on a physics course at Masaryk science that I am less familiar with. University in Brno. After a year and aIn the meantime, I was awarded a post­ half I applied for an Erasmus fellowship,doctoral fellowship at the Harvard- One great thing about ESO is the close which provides support for one yearSmithsonian Center for Astrophysics relationship between the science and the spent at foreign universities. Tempted by(CfA). I moved to Cambridge (Massachu­ cutting-edge facilities. Soon after joining the rumours of the great student lifesetts) in 2006 where I lived for three ESO, I was given the opportunity to go abroad, I chose the Freie Universität (FU)years. The experience was very reward­ for an observing run at APEX. The experi­ Berlin, and Prof. Baumgärtel’s group ating, both on a professional and a per­ ence turned out to be enriching beyond the Department of Physical Chemistry, assonal level. At the CfA I met prominent expectations and very exciting for many my temporary home for the academicscientists, including authors of books reasons: the impressive variety of science year 2002–3. Even though I then leftI had studied, and also a Nobel laureate programmes observed (from Solar System astronomy temporarily, since I was inves­who was sitting just a few offices down bodies to high-redshift galaxies), the tigating the nucleation rates of under­from mine! My research there focused on great team (family!) of staff astronomers cooled liquids at the FU (as part of my52 The Messenger 144 – June 2011
  • Astronomical NewsMaster’s programme), I thoroughly attempting to detect and characteriseenjoyed my time in Berlin. I was so exoplanetary atmospheres with near-impressed by the great city and its pul­ infrared instruments, using mostlysating life that I decided to stay for six HAWK-I, ISAAC and SOFI.more years and I also met my future wifeMartina there. ESO has given me a great opportunity to conduct my own research and to rein­The year 2006 signified a swift return force and foster collaborations. Evento astronomy when I landed a PhD posi­ though I am developing my own scientifiction in Prof. Heike Rauer’s group at the focus on exoplanetary atmospheres,German Aerospace Centre Berlin (DLR). I am still collaborating with my former col­My astronomy career started over again leagues on the BEST II telescope proj-with long observing runs on transiting ect. Furthermore, a couple of ESO pro­exoplanets with the BEST telescope posals submitted for the current andlocated at the Observatoire de Haute upcoming observing period are a resultProvence (OHP), France. Subsequently, of new and productive collaborationsI exchanged the OHP trips for a signifi­ with my current colleagues at the ESOcantly more distant destination, Cerro offices in Vitacura.Armazones in Chile, now the chosen sitefor the future E-ELT. I was very much At present, I am mid-way through myinvolved in the building, commissioning four-year contract. I have not yet decidedand setup of the new transit search Petr Kabath whether I would like to stay in Chile fortelescope BEST II, which started to oper­ the final year or go and spend the fourthate in 2007. Both telescopes were built world, I was delighted to receive the offer year somewhere else. Nevertheless,to support the space mission CoRoT, of an ESO Fellowship in 2009. Currently, while I am in Chile I am relishing thewhich is designed to detect transiting while performing operational duties at chance to experience this diverse culture,exoplanets. So the outcome of my PhD Paranal, I am assigned to the Unit Tele­ and appreciating the breathtaking natu-thesis is a fully operational robotic tele­ scopes 4 and 2. Besides these functional ral beauty of this captivating countryscope and the first detected candidates duties, I am working on my own scien­ while simultaneously being part of ESO.for transiting exoplanets. tific research on exoplanets. My major Of course all that would not be possible focus is on the detection and physical without the great support from my wifeSince the Chilean Atacama desert is characterisation of these distant worlds. Martina, to whom I am very thankful forofficially the astronomical capital of the Most recently, our team has been her endless patience with me.Report on theGarching ESO Fellow Days – 2011held at ESO Headquarters, Garching, Germany, 4–5 April 2011Eric Emsellem1 All the fellows briefly introduced them- main ESO sites in Chile and Germany.Pamela Klaassen1 selves and most presented recent These symposia took place every twoMichael West1 research results and perspectives. ESO years (the last one in 2009) alternately staff astronomers and students were in Santiago and Garching and gathered also invited to these presentations, together the full set of ESO Fellows.1 ESO which beautifully demonstrated the These meetings have been a great op- excellence of the science being con- portunity for science discussions, ducted by ESO Fellows. increased exchanges between all ESOFor the first of the newly formatted staff and have often led to new collabora­ESO Fellow Days, a total of 25 fellows, tions or personal science connections.including several ESO COFUND Fellows The Fellowship Symposia were originally Since ESO Fellow contracts last for threefrom Alma Regional Centres in Europe, designed to facilitate interactions or four years (in Garching and Santiagoand one fellow from Chile, gathered. between fellows spread over the two respectively), this frequency implied that The Messenger 144 – June 2011 53
  • Astronomical News Emsellem E. et al., Report on the “Garching ESO Fellow Days – 2011”a few unlucky ESO Fellows would only sent and discuss their field of research tions. Pamela Klaassen, Joel Vernet,travel across the Atlantic to visit the other and their scientific accomplishments. The Markus Kasper and Jochen Liske gavesite around the end of their Fellowship. presentations covered a wide range of presentations on ALMA, MUSE, KMOS, topics including protoplanetary discs, the SPHERE and the E-ELT respectively.In order to maximise the timeliness of evolution of debris discs around solar-these meetings, it was decided to change type stars, high- and low-mass star for­ A closed session, attended only by theto an annual basis, with two sessions mation from the formation of the cores to fellows and the head of the Office forof ESO Fellow Days each year, one at later stages, open clusters, super star Science in Garching, was organised toeach site, so that “new” fellows could clusters, feedback in starburst galaxies, discuss ways to improve the fellowshipmeet with the “old” ones. The more regu­ active galactic nuclei, quasars and strong programme in general and addressedlar meetings are an increased opportu- gravitational lensing studies (the full pro­ specific items such as training and thenity to advertise in-house the top-level gramme is available online1). job market. And of course, a social eventscience being done by ESO Fellows. It was organised: a dinner in the centrewas thus decided to organise a two­day The talks were of very high quality, and of Munich was a nice moment for moremeeting in Garching, for this, the first the rather informal atmosphere allowed informal interactions and to reflect on2011 German edition of the new format. attendees not too familiar with a field to the amazing science and projects beingThe chosen date also provided an op- grasp the essential ingredients and the conducted at ESO.portunity to attend the ALMA Community results emphasised by the speaker. ManyDays, taking place during same week interesting discussions took place, often(see Randall et al. p. 39). linking the differing areas of expertise of Acknowledgements people present in the room. This workshop, which we hope will be the first of aA total of 25 fellows attended the meet­ long series, would not have been possible withouting, including seven ESO ALMA– Long breaks helped to foster scientific the help of Christina Stoffer and the support from theCOFUND Fellows from various ALMA and social interactions not only among ESO IT Department. We warmly thank Joel Vernet, Markus Kasper and Jochen Liske for their excellentRegional Centres across Europe and the fellows themselves, but also with contributions.also one fellow from Chile. Most fellows other ESO staff. These breaks were alsogave a science presentation on their an opportunity for ESO astronomers toongoing and future work. This workshop introduce a future instrument or ESO Linkswas designed to allow relatively long facility, providing a privileged perspective 1 ESO Fellow Days 2011 programme: http://www.(half-hour) talks, giving ample time for the and a chance to seek specific answers eso.org/sci/meetings/2011/fellows_gar_2011/speakers to introduce themselves, pre­ to either technical or astrophysical ques­ schedule_fellow_days_gar2011.pdf Colour image of the Sc spiral galaxy NGC 3244 formed from FORS2 images in B, V and R filters. The bright star to the right is a nearby object in the Milky Way. The images were taken during the visit of the President of the Czech Republic Václav Klaus to Paranal. A framed print was presented to President Klaus, as a memento of his visit. Further details of the image can be found in Picture of the Week (potw1120) and of the President’s visit to Paranal in the Organisation Release eso1112.54 The Messenger 144 – June 2011
  • Astronomical News ESO European Organisation for Astronomical Research in the Southern Hemisphere ESO Fellowship Programme 2011/2012 The European Organisation for Astronomical Research in the Southern Hemi­ We offer an attractive remuneration package including a competitive salary sphere awards several postdoctoral fellowships each year. The goal of these and allowances (tax-free), comprehensive social benefits, and provide finan­ fellowships is to offer young outstanding scientists opportunities and facilities cial support for relocating families. to enhance their research programmes in close contact with the activities and staff at one of the world’s foremost observatories. The closing date for applications is 15 October 2011. In Garching, the fellowships start with an initial contract of one year followed Candidates will be notified of the results of the selection process between by a two-year extension (3 years total). The ESO Headquarters in Garching December 2011 and February 2012. Fellowships begin between April and near Munich, Germany, are situated in one of the most active research areas October of the year in which they are awarded. in Europe and have among the highest concentrations of astronomers. ESO offices are adjacent to the Max-Planck Institutes for Astrophysics and for Please apply by completing the web application form available at Extraterrestrial Physics and only a few kilometres away from the Observatory http://jobs.eso.org. Applications must include: of the Ludwig-Maximilian University. Additionally, ESO participates in the – your Curriculum Vitae with a list of publications (ONLY published papers, newly formed Excellence Cluster on Astrophysics on the Garching Campus, NOT papers in preparation); which brings together nearly 200 scientists to explore the origin and structure – your proposed research plan (maximum two pages); of the Universe. Consequently, ESO fellows in Garching have many opportu­ – a brief outline of your technical/observational experience (maximum one nities to interact and collaborate with astronomers at neighbouring institutes. page); In addition three letters of reference from persons familiar with your scientific In addition to the excellent scientific environment that will allow to develop work should be sent directly to ESO to vacancy@eso.org by the application their scientific skills, as part of the diverse training ESO offers, Garching fel­ deadline. lows spend up to 25% of their time in some functional work related to instru­ mentation, operations support, archive/virtual observatory, VLTI, ALMA, ELT, For more information about the fellowship programme and ESO’s astronomi­ public affairs, or science operations at the Observatory in Chile. cal research activities please see: http://www.eso.org/sci/activities/FeSt- overview/ESOfellowship.html. For a list of current ESO staff and fellows, and In Chile, the fellowships are granted for one year initially with an extension of their research interests please see: http://www.eso.org/sci/activities/person­ three additional years (4 years total). During the first three years, the fellows nel.html. Details of the Terms of Service for fellows including details of remu­ are assigned to one of the operations groups on Paranal, ALMA or APEX. Fel­ neration are available at: http://www.eso.org/public/employment/fellows.html lows contribute to the operations at a level of 80 nights per year at the Obser­ vatory. For further general information about fellowship applications, please see our Frequently Asked Questions – FAQs: http://www.eso.org/sci/activities/ Apart from opportunities for scientific interactions within ESO, fellows have FeSt-overview/ESOfellowship-faq.html. Questions not answered by the above the opportunity to collaborate with the rapidly growing Chilean astronomical FAQ page can be sent to: community as well as with astronomers at other international observatories located in Chile. The addition of a new ALMA building next to ESO’s Santiago For Garching: offices and the arrival of many astronomers and fellows working on the ALMA Eric Emsellem, Tel. +49 89 320 06-914, e-mail: eemselle@eso.org project has further enhanced the stimulating scientific environment available to ESO Chile fellows. For Chile: Michael West, Tel. +56 2 463 3254, email: mwest@eso.org During the fourth year there is little or no functional work and several options are provided. The fellow may be hosted by a Chilean institution (and will thus have access to all telescopes in Chile via the Chilean observing time). Alter­ natively, she/he may choose to spend the fourth year either at ESO’s astron­ omy centre in Santiago, or at the ESO Headquarters in Garching, or at any institute of astronomy/astrophysics in an ESO member state. The programme is open to applicants who will have achieved their PhD in astronomy, physics or related discipline before 1 November, 2012. Young sci­ entists from all astrophysical fields are welcome to apply. For all fellowships, scientific excellence is the prime selection criterion. The Messenger 144 – June 2011 55
  • ESO, the European Southern Observa- Contentstory, is the foremost intergovernmentalastronomy organisation in Europe. It The Organisationis supported by 15 countries: Austria, A. Bruch – Brazil’s Route to ESO Membership 2Belgium, Brazil, the Czech Republic,Denmark, France, Finland, Germany, Telescopes and InstrumentationItaly, the Netherlands, Portugal, Spain, R. Siebenmorgen et al. – The Science Impact of HAWK-I 9Sweden, Switzerland and the United C. Sandin et al. – p3d — A Data Reduction Tool for the Integral-fieldKingdom. ESO’s programme is focused Modes of VIMOS and FLAMES 13on the design, construction and opera- M. Arnaboldi et al. – Phase 3 — Handling Data Products from ESO Publiction of powerful ground-based observ- Surveys, Large Programmes and Other Contributions 17ing facilities. ESO operates three obser-vatories in Chile: at La Silla, at Paranal, Astronomical Sciencesite of the Very Large Telescope, and E. Lagadec et al. – A VISIR Mid-infrared Imaging Survey of Post-AGB Stars 21at Llano de Chajnantor. ESO is the M.-R. Cioni et al. – The VISTA Near-infrared YJKs Public Survey of theEuropean partner in the Atacama Large Magellanic Clouds System (VMC) 25Millimeter/submillimeter Array (ALMA) P. B. Stetson et al. – The Carina Dwarf Spheroidal Galaxy:under construction at Chajnantor. Cur- A Goldmine for Cosmology and Stellar Astrophysics 32rently ESO is engaged in the designof the European Extremely Large Astronomical NewsTelescope. S. Randal, L. Testi – Report on the Workshop “ALMA Community Days: Towards Early Science” 39The Messenger is published, in hard- S. Longmore et al. – Report on thecopy and electronic form, four times a “ALMA Early Science Massive Star Formation Workshop” 41year: in March, June, September and S. Mieske, M. Gieles – Report on the ESO Workshop “Dynamics ofDecember. ESO produces and distrib- Low-mass Stellar Systems: From Star Clusters to Dwarf Galaxies” 44utes a wide variety of media connected L. Schmidtobreic, M. R. Schreiber – Report on the Workshopto its activities. For further information, “The Evolution of Compact Binaries” 47including postal subscription to The D. Pierce-Price – ESO Participates in Germany’s Girls’ Day Activities 49Messenger, contact the ESO education Announcement of the ESO Workshopand Public Outreach Department at the “Ten Years of VLTI: From First Fringes to Core Science” 49following address: Personnel Movements 51 Fellows at ESO 52ESO Headquarters E. Emsellem et al. – Report on the “Garching ESO Fellow Days – 2011” 53Karl-Schwarzschild-Straße 2 ESO Fellowship Programme 2011/2012 5585748 Garching bei MünchenGermanyPhone +49 89 320 06-0information@eso.orgThe Messenger:Editor: Jeremy R. Walsh;Design: Jutta Boxheimer; Layout,Typesetting: Mafalda Martins;Graphics: Roberto Duque.www.eso.org/messenger/Printed by Mediengruppe UNIVERSALGrafische Betriebe München GmbHKirschstraße 16, 80999 MünchenGermany Front cover: The nearby low-mass star-forming region NGC 6729 centred on the variable star R Coronae Australis, is shown in a FORS2 two-colour compositeUnless otherwise indicated, all images image. Narrow band filter images centred on the emission lines of Hα (red) andin The Messenger are courtesy of ESO, [S ii] (blue) were combined. Some of the bluest features are shock-excited outflowsexcept authored contributions which (Herbig–Haro objects) from very young stars. The nebula NGC 6729 is opticallyare courtesy of the respective authors. variable and is a complex of gas, dust and embedded young and forming low- mass stars. The data were selected from the ESO archive by Sergey Stepanenko© ESO 2011 as part of the Hidden Treasures competition and this image was ranked third. SeeISSN 0722-6691 release eso1109 for more details.