ALMA observations of the HH 46/47 molecular outflow reveal striking differences between the blue and red lobes. The blue lobe morphology and kinematics are consistent with entrainment by a wide-angle wind, while the red lobe shows a more complex structure with evidence of entrainment by both a wide-angle wind and collimated episodic winds. Three major clumps along the red lobe axis have velocity distributions consistent with prompt entrainment by periodic mass ejection episodes occurring every few hundred years. Position-velocity cuts show velocity gradients increasing toward the outflow axis, inconsistent with outflow rotation.
Mapping the complex_kinematics_of_l_lobjects_in_the_orion_nebulaSérgio Sacani
This document presents a study of the kinematics of two LL Orionis-type objects (LL objects) in the Orion nebula, LL 1 and LL 2, and their associated Herbig-Haro jets HH 888 and HH 505. The authors combine long-slit spectroscopic observations of the objects with proper motion measurements to construct 3D velocity maps. The maps reveal:
1) Low velocities (10-20 km/s) in the stellar bowshocks of LL 1 and LL 2, with LL 1 showing symmetric motions and LL 2 showing asymmetric motions following nebula gradients.
2) Jet knot velocities over 200 km/s near the stars declining to under 100 km/s farther out in HH 8
The shadow _of_the_flying_saucer_a_very_low_temperature_for_large_dust_grainsSérgio Sacani
Os astrónomos usaram o ALMA e os telescópios do IRAM para fazer a primeira medição direta da temperatura dos grãos de poeira grandes situados nas regiões periféricas de um disco de formação planetária que se encontra em torno de uma estrela jovem. Ao observar de forma inovadora um objeto cujo nome informal é Disco Voador, os astrónomos descobriram que os grãos de poeira são muito mais frios do que o esperado: -266º Celsius. Este resultado surpreendente sugere que os modelos teóricos destes discos precisam de ser revistos.
Uma equipa internacional liderada por Stephane Guilloteau do Laboratoire d´Astrophysique de Bordeaux, França, mediu a temperatura de enormes grãos de poeira que se encontram em torno da jovem estrela 2MASS J16281370-2431391 na região de formação estelar Rho Ophiuchi, a cerca de 400 anos-luz de distância da Terra.
Esta estrela encontra-se rodeada por um disco de gás e poeira — chamado disco protoplanetário, uma vez que se encontra na fase inicial da formação de um sistema planetário. Este disco é visto de perfil quando observado a partir da Terra e a sua aparência em imagens no visível levou a que se lhe desse o nome informal de Disco Voador.
Os astrónomos utilizaram o ALMA para observar o brilho emitido pelas moléculas de monóxido de carbono no disco da 2MASS J16281370-2431391. As imagens revelaram-se extremamente nítidas e descobriu-se algo estranho — em alguns casos o sinal recebido era negativo. Normalmente um sinal negativo é fisicamente impossível, mas neste caso existe uma explicação, que leva a uma conclusão surpreendente.
Todo mundo sabe que os raios produzidos pela Estrela da Morte em Guerra nas Estrelas não pode existir na vida real, porém no universo existem fenômenos que as vezes conseguem superar até a mais surpreendente ficção.
A galáxia Pictor A, é um desses objetos que possuem fenômenos tão espetaculares quanto aqueles exibidos no cinema. Essa galáxia localiza-se a cerca de 500 milhões de anos-luz da Terra e possui um buraco negro supermassivo no seu centro. Uma grande quantidade de energia gravitacional é lançada, à medida que o material cai em direção ao horizonte de eventos, o ponto sem volta ao redor do buraco negro. Essa energia produz um enorme jato de partículas que viajam a uma velocidade próxima da velocidade da luz no espaço intergaláctico, chamado de jato relativístico.
Para obter imagens desse jato, os cientistas usaram o Observatório de Raios-X Chandra, da NASA várias vezes durante 15 anos. Os dados do Chandra, apresentados em azul nas imagens, foram combinados com os dados obtidos em ondas de rádio a partir do Australia Telescope Compact Array, e são aparesentados em vermelho nas imagens.
Detectcion of noble_gas_molecular_ion_arh_in_the_crab_nebulaSérgio Sacani
Scientists detected emission lines from the ionized argon hydride (36ArH+) molecule in spectra of the Crab Nebula obtained with the Herschel Space Observatory. The detection of 36ArH+ confirms that argon originated from explosive nucleosynthesis during the core-collapse supernova that created the Crab Nebula. The likely excitation mechanism is electron collisions in partially ionized regions with electron densities of a few hundred per cubic centimeter. This is the first detection of a noble gas molecule in space.
The document summarizes Spitzer observations of the supernova remnant IC 443. The MIPS images show the remnant's morphology in great detail, resembling a shell or loop. The dust temperature ranges from 18-30 K based on the 70/160um ratio. IRS spectroscopy confirms shock-excited atomic and molecular emission, with shock velocities of 60-90 km/s. H2 excitation diagrams show temperatures of 300-600 K and column densities varying across the remnant.
Herschel far infrared_spectroscopy_of_the_galactic_centerSérgio Sacani
The document summarizes observations from the Herschel Space Observatory of the Galactic Center region, focusing on a spectral scan toward Sagittarius A*. Key findings include:
1) Strong emission from atomic fine structure lines and rotationally excited lines of molecules like CO, H2O and HCO+ are detected.
2) The excitation of the CO ladder is consistent with either a hot isothermal gas component at 103.1 K and 104 cm-3, or a distribution of warmer gas at higher densities, with most CO at 300 K.
3) The detected molecular features suggest heating is from a combination of UV irradiation and shocks in the gas, rather than very enhanced X-ray or cosmic
A new universal formula for atoms, planets, and galaxiesIOSR Journals
In this paper a new universal formula about the rotation velocity distribution of atoms, planets, and galaxies is presented. It is based on a new general formula based on the relativistic Schwarzschild/Minkowski metric, where it has been possible to obtain expressions for the rotation velocity - and mass distribution versus the distance to the atomic nucleus, planet system centre, and galactic centre. A mathematical proof of this new formula is also given. This formula is divided into a Keplerian(general relativity)-and a relativistic(special relativity) part. For the atomic-and planet systems the Keplerian distribution is followed, which is also in accordance with observations.
According to the rotation velocity distribution of the galaxies the rotation velocity increases very rapidly from the centre and reaches a plateau which is constant out to a great distance from the centre. This is in accordance with observations and is also in accordance with the main structure of rotation velocity versus distance from different galaxy measurements.
Computer simulations were also performed to establish and verify the rotation velocity distributions in the atomic – planetary- and galaxy system, according to this paper. These computer simulations are in accordance with observations in two and three dimensions. It was also possible to study the matching percentage in these calculations showing a much higher matching percentage between theoretical and observational values by this new formula.
Observations of gas_flows_inside_a_protoplanetary_gapSérgio Sacani
1) ALMA observations of the protoplanetary disk around HD 142527 reveal diffuse CO gas and denser HCO+ filaments inside the dust gap.
2) The HCO+ filaments extend from the outer disk towards the inner disk and star, indicating gas flowing across the gap.
3) Estimates of the gas flow rate through the filaments are sufficient to sustain the observed rate of accretion onto the star, supporting the interpretation that the filaments are planet-induced gap-crossing accretion streams.
Mapping the complex_kinematics_of_l_lobjects_in_the_orion_nebulaSérgio Sacani
This document presents a study of the kinematics of two LL Orionis-type objects (LL objects) in the Orion nebula, LL 1 and LL 2, and their associated Herbig-Haro jets HH 888 and HH 505. The authors combine long-slit spectroscopic observations of the objects with proper motion measurements to construct 3D velocity maps. The maps reveal:
1) Low velocities (10-20 km/s) in the stellar bowshocks of LL 1 and LL 2, with LL 1 showing symmetric motions and LL 2 showing asymmetric motions following nebula gradients.
2) Jet knot velocities over 200 km/s near the stars declining to under 100 km/s farther out in HH 8
The shadow _of_the_flying_saucer_a_very_low_temperature_for_large_dust_grainsSérgio Sacani
Os astrónomos usaram o ALMA e os telescópios do IRAM para fazer a primeira medição direta da temperatura dos grãos de poeira grandes situados nas regiões periféricas de um disco de formação planetária que se encontra em torno de uma estrela jovem. Ao observar de forma inovadora um objeto cujo nome informal é Disco Voador, os astrónomos descobriram que os grãos de poeira são muito mais frios do que o esperado: -266º Celsius. Este resultado surpreendente sugere que os modelos teóricos destes discos precisam de ser revistos.
Uma equipa internacional liderada por Stephane Guilloteau do Laboratoire d´Astrophysique de Bordeaux, França, mediu a temperatura de enormes grãos de poeira que se encontram em torno da jovem estrela 2MASS J16281370-2431391 na região de formação estelar Rho Ophiuchi, a cerca de 400 anos-luz de distância da Terra.
Esta estrela encontra-se rodeada por um disco de gás e poeira — chamado disco protoplanetário, uma vez que se encontra na fase inicial da formação de um sistema planetário. Este disco é visto de perfil quando observado a partir da Terra e a sua aparência em imagens no visível levou a que se lhe desse o nome informal de Disco Voador.
Os astrónomos utilizaram o ALMA para observar o brilho emitido pelas moléculas de monóxido de carbono no disco da 2MASS J16281370-2431391. As imagens revelaram-se extremamente nítidas e descobriu-se algo estranho — em alguns casos o sinal recebido era negativo. Normalmente um sinal negativo é fisicamente impossível, mas neste caso existe uma explicação, que leva a uma conclusão surpreendente.
Todo mundo sabe que os raios produzidos pela Estrela da Morte em Guerra nas Estrelas não pode existir na vida real, porém no universo existem fenômenos que as vezes conseguem superar até a mais surpreendente ficção.
A galáxia Pictor A, é um desses objetos que possuem fenômenos tão espetaculares quanto aqueles exibidos no cinema. Essa galáxia localiza-se a cerca de 500 milhões de anos-luz da Terra e possui um buraco negro supermassivo no seu centro. Uma grande quantidade de energia gravitacional é lançada, à medida que o material cai em direção ao horizonte de eventos, o ponto sem volta ao redor do buraco negro. Essa energia produz um enorme jato de partículas que viajam a uma velocidade próxima da velocidade da luz no espaço intergaláctico, chamado de jato relativístico.
Para obter imagens desse jato, os cientistas usaram o Observatório de Raios-X Chandra, da NASA várias vezes durante 15 anos. Os dados do Chandra, apresentados em azul nas imagens, foram combinados com os dados obtidos em ondas de rádio a partir do Australia Telescope Compact Array, e são aparesentados em vermelho nas imagens.
Detectcion of noble_gas_molecular_ion_arh_in_the_crab_nebulaSérgio Sacani
Scientists detected emission lines from the ionized argon hydride (36ArH+) molecule in spectra of the Crab Nebula obtained with the Herschel Space Observatory. The detection of 36ArH+ confirms that argon originated from explosive nucleosynthesis during the core-collapse supernova that created the Crab Nebula. The likely excitation mechanism is electron collisions in partially ionized regions with electron densities of a few hundred per cubic centimeter. This is the first detection of a noble gas molecule in space.
The document summarizes Spitzer observations of the supernova remnant IC 443. The MIPS images show the remnant's morphology in great detail, resembling a shell or loop. The dust temperature ranges from 18-30 K based on the 70/160um ratio. IRS spectroscopy confirms shock-excited atomic and molecular emission, with shock velocities of 60-90 km/s. H2 excitation diagrams show temperatures of 300-600 K and column densities varying across the remnant.
Herschel far infrared_spectroscopy_of_the_galactic_centerSérgio Sacani
The document summarizes observations from the Herschel Space Observatory of the Galactic Center region, focusing on a spectral scan toward Sagittarius A*. Key findings include:
1) Strong emission from atomic fine structure lines and rotationally excited lines of molecules like CO, H2O and HCO+ are detected.
2) The excitation of the CO ladder is consistent with either a hot isothermal gas component at 103.1 K and 104 cm-3, or a distribution of warmer gas at higher densities, with most CO at 300 K.
3) The detected molecular features suggest heating is from a combination of UV irradiation and shocks in the gas, rather than very enhanced X-ray or cosmic
A new universal formula for atoms, planets, and galaxiesIOSR Journals
In this paper a new universal formula about the rotation velocity distribution of atoms, planets, and galaxies is presented. It is based on a new general formula based on the relativistic Schwarzschild/Minkowski metric, where it has been possible to obtain expressions for the rotation velocity - and mass distribution versus the distance to the atomic nucleus, planet system centre, and galactic centre. A mathematical proof of this new formula is also given. This formula is divided into a Keplerian(general relativity)-and a relativistic(special relativity) part. For the atomic-and planet systems the Keplerian distribution is followed, which is also in accordance with observations.
According to the rotation velocity distribution of the galaxies the rotation velocity increases very rapidly from the centre and reaches a plateau which is constant out to a great distance from the centre. This is in accordance with observations and is also in accordance with the main structure of rotation velocity versus distance from different galaxy measurements.
Computer simulations were also performed to establish and verify the rotation velocity distributions in the atomic – planetary- and galaxy system, according to this paper. These computer simulations are in accordance with observations in two and three dimensions. It was also possible to study the matching percentage in these calculations showing a much higher matching percentage between theoretical and observational values by this new formula.
Observations of gas_flows_inside_a_protoplanetary_gapSérgio Sacani
1) ALMA observations of the protoplanetary disk around HD 142527 reveal diffuse CO gas and denser HCO+ filaments inside the dust gap.
2) The HCO+ filaments extend from the outer disk towards the inner disk and star, indicating gas flowing across the gap.
3) Estimates of the gas flow rate through the filaments are sufficient to sustain the observed rate of accretion onto the star, supporting the interpretation that the filaments are planet-induced gap-crossing accretion streams.
Evidence for Long-Lasting Electrical Leader Discharges in NonSpecular Meteor ...researchinventy
Unusual, non-specular, fast-movingmeteortrail echoes are observed in the summer polar upper mesosphere near 90 km.Usually, at mid-latitudes, field-aligned irregularities cause non-specular trails, while in the polar region long-lasting irregularities are possibly sustained by charged meteor dust.The unusual meteor trails propagate downward and upward at speeds of 3.3-6.4 kms-1 along a slanted path length of 10.4 km between 87-93 km altitudes, merging in the middle and lasting for 8-10s. Here we propose that an electrical discharge is responsible for these trails. The corresponding horizontal electric field for the observed speeds is estimated up to 16.3 Vm-1 at 90 km.Both the long-lasting merging of two fast-moving plasma trails and the modest speed compared to those (~104 -105 ms -1 ) of lightning leader process and of jets (< 400 ms) occurring above thunderclouds likely suggest a new type of meteor-trail leader discharge occurring in the summer polar upper mesosphere
Gas physical conditions_and_kinematics_of_the_giant_outflow_ou4Sérgio Sacani
This document discusses observations of the giant outflow Ou4, located near the HII region Sh 2-129. Spectroscopic observations of Ou4 reveal shock-excited gas consistent with a fast collimated outflow. Mid-infrared images show a bubble of hot dust emission inside Ou4 that corresponds to [OIII] features. The distance and properties of Ou4 are consistent with it being launched about 90,000 years ago from the young massive star cluster HR 8119, located at the center of Sh 2-129. However, the possibility that Ou4 is a planetary nebula or resulted from an eruptive event on a massive asymptotic giant branch star cannot be ruled out.
Galaxy dynamics and the mass density of the universeSérgio Sacani
Dynamical evidence accumulated over the
past 20 years has convinced astronomers that luminous matter
in a spiral galaxy constitutes no more than 10% of the mass of
a galaxy. An additional 90% is inferred by its gravitational
effect on luminous material. Here I review recent observations
concerning the distribution of luminous and nonluminous
matter in the Milky Way, in galaxies, and in galaxy clusters.
Observations of neutral hydrogen disks, some extending in
radius several times the optical disk, confirm that a massive
dark halo is a major component of virtually every spiral. A
recent surprise has been the discovery that stellar and gas
motions in ellipticals are enormously complex. To date, only for
a few spheroidal galaxies do the velocities extend far enough to
probe the outer mass distribution. But the diverse kinematics
of inner cores, peripheral to deducing the overall mass distribution,
offer additional evidence that ellipticals have acquired
gas-rich systems after initial formation. Dynamical results are
consistent with a low-density universe, in which the required
dark matter could be baryonic. On smallest scales of galaxies
[10 kiloparsec (kpc); H. = 50 kmsec'lmegaparsec'11 the
luminous matter constitutes only 1% of the closure density. On
scales greater than binary galaxies (i.e., .100 kpc) all systems
indicate a density -10% of the closure density, a density
consistent with the low baryon density in the universe. If
large-scale motions in the universe require a higher mass
density, these motions would constitute the first dynamical
evidence for nonbaryonic matter in a universe of higher
density.
The Internal Structure of Asteroid (25143) Itokawa as Revealed by Detection o...WellingtonRodrigues2014
- The authors detected an acceleration in the rotation rate of asteroid (25143) Itokawa through photometric observations spanning 2001 to 2013.
- By measuring rotational phase offsets between observed and modeled lightcurves, they found a YORP acceleration of 3.54 ± 0.38 × 10−8 rad day−2, equivalent to a decrease in the asteroid's rotation period of about 45 ms per year.
- Thermophysical modeling of the detailed shape model from the Hayabusa spacecraft could not reconcile the observed YORP strength unless the asteroid's center of mass is shifted by about 21 m along its long axis. This suggests Itokawa has two components with different densities that merged, either from a
The ASTRODEEP Frontier Fields catalogues II. Photometric redshifts and rest f...Sérgio Sacani
This document describes a public release of photometric redshifts and galaxy properties from multi-wavelength data in the Abell-2744 and MACS-J0416 galaxy cluster fields observed as part of the Frontier Fields program. Photometric redshifts were estimated using six different methods and have an accuracy of 3-5%. Accounting for gravitational lensing magnification, the H-band number counts agree with CANDELS at bright magnitudes but extend to intrinsically fainter galaxies of H=32-33. The Frontier Fields data allow probing galaxy stellar masses 0.5-1.5 dex lower than in wide fields, including sources with masses of 107-108 solar masses at z>5. Star formation rates can be detected 1
IOSR Journal of Applied Physics (IOSR-JAP) is an open access international journal that provides rapid publication (within a month) of articles in all areas of physics and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in applied physics. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
1) Researchers observed 15 transits of the exoplanet GJ 1214b using the Hubble Space Telescope to measure its transmission spectrum from 1.1 to 1.7 microns.
2) The transmission spectrum was featureless, inconsistent with cloud-free atmospheres dominated by water, methane, carbon monoxide, nitrogen, or carbon dioxide.
3) The most likely explanation for the featureless spectrum is the presence of high-altitude clouds in the planet's atmosphere, which block the transmission of stellar light through the lower atmosphere.
High-resolution UV/Optical/IR Imaging of Jupiter in 2016–2019Sérgio Sacani
Imaging observations of Jupiter with high spatial resolution were acquired beginning in 2016, with a cadence of 53
days to coincide with atmospheric observations of the Juno spacecraft during each perijove pass. The Wide Field
Camera 3 (WFC3) aboard the Hubble Space Telescope (HST) collected Jupiter images from 236 to 925 nm in 14
filters. The Near-Infrared Imager (NIRI) at Gemini North imaged Jovian thermal emission using a lucky-imaging
approach (co-adding the sharpest frames taken from a sequence of short exposures), using the M′ filter at 4.7 μm.
We discuss the data acquisition and processing and an archive collection that contains the processed WFC3 and
NIRI data (doi:10.17909/T94T1H). Zonal winds remain steady over time at most latitudes, but significant
evolution of the wind profile near 24°N in 2016 and near 15°S in 2017 was linked with convective superstorm
eruptions. Persistent mesoscale waves were seen throughout the 2016–2019 period. We link groups of lightning
flashes observed by the Juno team with water clouds in a large convective plume near 15°S and in cyclones near
35°N–55°N. Thermal infrared maps at the 10.8 micron wavelength obtained at the Very Large Telescope show
consistent high brightness temperature anomalies, despite a diversity of aerosol properties seen in the HST data.
Both WFC3 and NIRI imaging reveal depleted aerosols consistent with downwelling around the periphery of the
15°S storm, which was also observed by the Atacama Large Millimeter/submillimeter Array. NIRI imaging of
the Great Red Spot shows that locally reduced cloud opacity is responsible for dark features within the vortex. The
HST data maps multiple concentric polar hoods of high-latitude hazes.
A highly magnetized twin-jet base pinpoints a supermassive black holeSérgio Sacani
Supermassive black holes (SMBH) are essential for the production of jets in radio-loud active galactic nuclei (AGN). Theoretical
models based on (Blandford & Znajek 1977, MNRAS, 179, 433) extract the rotational energy from a Kerr black hole, which could
be the case for NGC1052, to launch these jets. This requires magnetic fields on the order of 103 G to 104 G. We imaged the vicinity
of the SMBH of the AGN NGC1052 with the Global Millimetre VLBI Array and found a bright and compact central feature that is
smaller than 1.9 light days (100 Schwarzschild radii) in radius. Interpreting this as a blend of the unresolved jet bases, we derive the
magnetic field at 1 Schwarzschild radius to lie between 200 G and 8:3 104 G consistent with Blandford & Znajek models.
Far infrared dust_temperatures_and_column_densities_of_the_malt90_molecular_c...Sérgio Sacani
Estrelas como o Sol começam suas vidas como núcleos densos e frios de gás e poeira que colapsam sob a influência da gravidade até que a fusão possa iniciar. Esses núcleos contêm de centenas a milhares de vezes a massa do Sol de material e têm uma densidade de gás mil vezes maior do que as regiões interestelares típicas (o valor típico é de uma molécula por centímetro cúbico). Como o processo de colapso ocorre nesses núcleos é algo pouco entendido, desde o número de estrelas que se formam, até os fatores que determinam suas massas, bem como a escala de tempo detalhada para o nascimento de uma estrela. O material, por exemplo, pode simplesmente cair livremente para o centro do núcleo, mas em cenários mais realistas, a queda é inibida pel pressão do gás aquecido, dos movimentos tubulentos, os campos magnéticos, ou alguma combinação desses fatores.
Os astrônomos estão estudando ativamente essas questões, observando jovens estrelas no processo de nascimento. A poeira nesses núcleos natais (ou aglomerados), contudo, faz com que o material seja opaco para a luz óptica, necessitando de observações em outros comprimentos de onda, em particular no infravermelho, submilimétrico, e rádio. nos estágios iniciais da formação das estrelas, uma estrela embrionária aquece a nuvem de poeira ao redor a temperaturas entre 10 e 30 graus Kelvin, antes que os ventos estelares e a radiação, sopre o material para longe expondo a estrela recém-nascida. Os astrônomos do CfA Andres Guzman e Howard Smith, junto com seus colegas, completaram uma análise de 3246 núcleos de formação de estrelas, a maior amostragem já feita. Os núcleos frios foram descobertos com o Submillmetre-Wavelength Sky Survey APEX, e então observados em 16 linhas espectrais submilimétricas, a informação espectral permitiu que os astrônomos pudessem determinar a distância para cada núcleo, bem como pesquisar a química e os movimentos internos do gás. O novo artigo, combina esses resultados com medidas do infravermelho distante feitas pelo Observatório Espacial Herschel da ESA. Os dados do Herschel permitiram que os cientistas calculassem a densidade da poeira, a massa e a temperatura de cada núcleo, o grande conjunto de dados então permitiu comparações estatísticas úteis entre os núcleos com vários parâmetros.
Serendipitous discovery of an extended xray jet without a radio counterpart i...Sérgio Sacani
A recent Chandra observation of the nearby galaxy cluster Abell 585 has led to the discovery of
an extended X-ray jet associated with the high-redshift background quasar B3 0727+409, a luminous
radio source at redshift z = 2:5. This is one of only few examples of high-redshift X-ray jets known
to date. It has a clear extension of about 1200, corresponding to a projected length of 100 kpc, with
a possible hot spot located 3500 from the quasar. The archival high resolution VLA maps surprisingly
reveal no extended jet emission, except for one knot about 1:400 from the quasar. The high X-ray to
radio luminosity ratio for this source appears consistent with the / (1 + z)4 amplication expected
from the inverse Compton radiative model. This serendipitous discovery may signal the existence
of an entire population of similar systems with bright X-ray and faint radio jets at high redshift, a
selection bias which must be accounted for when drawing any conclusions about the redshift evolution
of jet properties and indeed about the cosmological evolution of supermassive black holes and active
galactic nuclei in general.
A wide and collimated radio jet in 3C84 on the scale of a few hundred gravita...Sérgio Sacani
This document summarizes key findings from a study of the radio jet in galaxy 3C84 using very long baseline interferometry (VLBI) with the RadioAstron space telescope. The observations resolve the edge-brightened jet structure only 30 microarcseconds from the core, corresponding to ~350 gravitational radii. This is 10 times closer to the central engine than previous ground-based observations. The measurements show the jet has an initially wide opening angle of 130 degrees that rapidly collimates into an almost cylindrical profile out to ~8,000 gravitational radii. The wide jet observed so close to the core poses challenges for models where the jet originates from the black hole ergosphere.
Evidence for a_distant_giant_planet_in_the_solar_systemSérgio Sacani
A descoberta de um novo planeta, atualmente não é uma manchete que chama tanto assim a atenção das pessoas. Muito disso, graças ao Telescópio Espacial Kepler, que já descobriu quase 2000 exoplanetas e todo instante uma nova descoberta é anunciada, certo? Mais ou menos, a descoberta anunciada hoje, dia 20 de Janeiro de 2016, é um pouco diferente, pois não se trata de um exoplaneta, e sim de um novo planeta no Sistema Solar, e esse é um fato que intriga os astrônomos a muitos e muitos anos.
Porém, temos que ir com calma com esses anúncios. No artigo aceito para publicação no The Astronomical Journal (artigo no final do post), os autores, Mike Brown e Konstantin Batygin, do Instituto de Tecnologia da Califórnia, apresentaram o que eles dizem ser evidências circunstâncias fortes para a existência de um grande planeta ainda não descoberto, talvez, com uma massa 10 vezes a massa da Terra, orbitando os confins do nosso Sistema Solar, muito além da órbita de Plutão. Os cientistas inferiram sua presença, por meio de anomalias encontradas nas órbitas de seis objetos do chamado Cinturão de Kuiper.
O objeto, que os pesquisadores estão chamando de Planeta Nove, não chega muito perto do Sol, no ponto mais próximo da sua órbita ele fica a 30.5 bilhões de quilômetros, ou seja, cinco vezes a distância entre o Sol e Plutão. Apesar do seu grande tamanho, ele é muito apagado, e por isso ninguém até o momento conseguiu observá-lo.
Não existe ainda uma confirmação observacional da descoberta, mas as evidências são tão fortes que fizeram com que outros especialistas como Chad Trujilo do Observatório Gemini no Havaí e David Nesvorny, do Southwest Research Institute em Boulder no Colorado, ficassem impressionados e bem convencidos de que deve mesmo haver um grande planeta nas fronteiras da nossa vizinhança cósmica.
PROBING FOR EVIDENCE OF PLUMES ON EUROPA WITH HST/STISSérgio Sacani
Roth et al. (2014a) reported evidence for plumes of water venting from a southern high latitude
region on Europa – spectroscopic detection of off-limb line emission from the dissociation
products of water. Here, we present Hubble Space Telescope (HST) direct images of Europa in
the far ultraviolet (FUV) as it transited the smooth face of Jupiter, in order to measure absorption
from gas or aerosols beyond the Europa limb. Out of ten observations we found three in which
plume activity could be implicated. Two show statistically significant features at latitudes similar
to Roth et al., and the third, at a more equatorial location. We consider potential systematic
effects that might influence the statistical analysis and create artifacts, and are unable to find any
that can definitively explain the features, although there are reasons to be cautious. If the
apparent absorption features are real, the magnitude of implied outgassing is similar to that of the
Roth et al. feature, however the apparent activity appears more frequently in our data.
This document describes observations of the Seyfert 1 galaxy Mrk 509 using the Cosmic Origins Spectrograph (COS) on the Hubble Space Telescope (HST). The observations detected absorption features in the ultraviolet spectrum, which are attributed to outflowing gas from the active galactic nucleus as well as gas in the galaxy's interstellar medium and halo. The COS observations provide higher signal-to-noise and resolution than previous observations, detecting additional complexity in the absorption features. Variability in some features constrains the distances of absorbing gas components to be less than 250 pc and 1.5 kpc from the active nucleus. The absorption lines only partially cover the emission from the active nucleus, possibly due to
The large-scale nebular pattern of a superwind binary in an eccentric orbitSérgio Sacani
Preplanetary nebulae and planetary nebulae are evolved,
mass-losing stellar objects that show a wide variety of morphologies.
Many of these nebulae consist of outer structures
that are nearly spherical (spiral/shell/arc/halo) and inner
structures that are highly asymmetric (bipolar/multipolar)1,2.
The coexistence of such geometrically distinct structures is
enigmatic because it hints at the simultaneous presence of
both wide and close binary interactions, a phenomenon that
has been attributed to stellar binary systems with eccentric
orbits3. Here, we report high-resolution molecular line observations
of the circumstellar spiral-shell pattern of AFGL 3068,
an asymptotic giant branch star transitioning to the preplanetary
nebula phase. The observations clearly reveal that the
dynamics of the mass loss is influenced by the presence of an
eccentric-orbit binary. This quintessential object opens a window
on the nature of deeply embedded binary stars through
the circumstellar spiral-shell patterns that reside at distances
of several thousand au from the stars.
This document is the table of contents and introduction for a science fair project analyzing solar p-mode travel times measured using sodium and potassium spectra. The student took images of the sun using these two spectra, which correspond to different solar altitudes. Power spectra were generated and trumpet structures were compared by fitting circles to cross-sections. Radius vs. frequency plots showed the sodium radii were generally larger. While this provides evidence against the hypothesis that travel times are the same, more data is needed for a definitive conclusion on whether p-waves are fully evanescent.
Small scatter and_nearly_isothermal_mass_profiles_to_four_half_light_radii_fr...Sérgio Sacani
This document summarizes the results of a study analyzing the total mass density profiles of 14 early-type galaxies using two-dimensional stellar kinematic data out to large radii of 2-6 half-light radii. The study finds that the total density profiles are well described by a nearly-isothermal power law with density proportional to radius from 0.1 to at least 4 half-light radii. The average logarithmic slope is -2.19 with a small scatter of only 0.11. This places tight constraints on galaxy formation models and illustrates the power of extended two-dimensional stellar kinematic observations.
Dust in the_polar_region_as_a_major_contributor_to_the_infrared_emission_of_a...Sérgio Sacani
The mid-infrared emission of the active galactic nucleus NGC 3783 was observed using interferometry over multiple epochs, providing dense coverage of position angles and baselines. The emission was found to be strongly elongated along a position angle of -52 degrees, closely aligned with the polar axis orientation of -45 degrees. The half-light radii were measured to be 20.0 mas by 6.7 mas, corresponding to an axis ratio of 3:1. This implies that 60-90% of the 8-13 micron emission is from the polar-elongated component. The observations support a scenario where the majority of mid-infrared emission in Seyfert galaxies originates from a dusty wind in the polar region,
3C 273 was one of the first quasars discovered in 1963. It remains one of the brightest and best studied quasars. It is located approximately 3 billion light years from Earth and radiates energy equivalent to 1014 times the luminosity of the Sun. 3C 273 plays a key role in understanding the nature of quasars as powered by accretion disks around supermassive black holes. It continues to be intensely observed across the electromagnetic spectrum to better understand the physics occurring in these energetic and distant cosmic objects.
One tenth solar_abundances_along_the_body_of-the_streamSérgio Sacani
This document summarizes a study that analyzed spectra from four background quasars to measure the chemical abundances along the Magellanic Stream. Two key findings are:
1) The sightlines toward RBS 144 and NGC 7714 yielded metallicities of around 0.1 times the solar value, indicating a uniform low abundance along the main body of the Stream. This supports models where the Stream was stripped from the SMC around 1-2.5 billion years ago when the SMC had a metallicity of around 0.1 solar.
2) A higher metallicity of around 0.5 solar was found in the inner Stream toward Fairall 9, sampling a filament traced to the LMC. This shows the bifurc
Evidence for Long-Lasting Electrical Leader Discharges in NonSpecular Meteor ...researchinventy
Unusual, non-specular, fast-movingmeteortrail echoes are observed in the summer polar upper mesosphere near 90 km.Usually, at mid-latitudes, field-aligned irregularities cause non-specular trails, while in the polar region long-lasting irregularities are possibly sustained by charged meteor dust.The unusual meteor trails propagate downward and upward at speeds of 3.3-6.4 kms-1 along a slanted path length of 10.4 km between 87-93 km altitudes, merging in the middle and lasting for 8-10s. Here we propose that an electrical discharge is responsible for these trails. The corresponding horizontal electric field for the observed speeds is estimated up to 16.3 Vm-1 at 90 km.Both the long-lasting merging of two fast-moving plasma trails and the modest speed compared to those (~104 -105 ms -1 ) of lightning leader process and of jets (< 400 ms) occurring above thunderclouds likely suggest a new type of meteor-trail leader discharge occurring in the summer polar upper mesosphere
Gas physical conditions_and_kinematics_of_the_giant_outflow_ou4Sérgio Sacani
This document discusses observations of the giant outflow Ou4, located near the HII region Sh 2-129. Spectroscopic observations of Ou4 reveal shock-excited gas consistent with a fast collimated outflow. Mid-infrared images show a bubble of hot dust emission inside Ou4 that corresponds to [OIII] features. The distance and properties of Ou4 are consistent with it being launched about 90,000 years ago from the young massive star cluster HR 8119, located at the center of Sh 2-129. However, the possibility that Ou4 is a planetary nebula or resulted from an eruptive event on a massive asymptotic giant branch star cannot be ruled out.
Galaxy dynamics and the mass density of the universeSérgio Sacani
Dynamical evidence accumulated over the
past 20 years has convinced astronomers that luminous matter
in a spiral galaxy constitutes no more than 10% of the mass of
a galaxy. An additional 90% is inferred by its gravitational
effect on luminous material. Here I review recent observations
concerning the distribution of luminous and nonluminous
matter in the Milky Way, in galaxies, and in galaxy clusters.
Observations of neutral hydrogen disks, some extending in
radius several times the optical disk, confirm that a massive
dark halo is a major component of virtually every spiral. A
recent surprise has been the discovery that stellar and gas
motions in ellipticals are enormously complex. To date, only for
a few spheroidal galaxies do the velocities extend far enough to
probe the outer mass distribution. But the diverse kinematics
of inner cores, peripheral to deducing the overall mass distribution,
offer additional evidence that ellipticals have acquired
gas-rich systems after initial formation. Dynamical results are
consistent with a low-density universe, in which the required
dark matter could be baryonic. On smallest scales of galaxies
[10 kiloparsec (kpc); H. = 50 kmsec'lmegaparsec'11 the
luminous matter constitutes only 1% of the closure density. On
scales greater than binary galaxies (i.e., .100 kpc) all systems
indicate a density -10% of the closure density, a density
consistent with the low baryon density in the universe. If
large-scale motions in the universe require a higher mass
density, these motions would constitute the first dynamical
evidence for nonbaryonic matter in a universe of higher
density.
The Internal Structure of Asteroid (25143) Itokawa as Revealed by Detection o...WellingtonRodrigues2014
- The authors detected an acceleration in the rotation rate of asteroid (25143) Itokawa through photometric observations spanning 2001 to 2013.
- By measuring rotational phase offsets between observed and modeled lightcurves, they found a YORP acceleration of 3.54 ± 0.38 × 10−8 rad day−2, equivalent to a decrease in the asteroid's rotation period of about 45 ms per year.
- Thermophysical modeling of the detailed shape model from the Hayabusa spacecraft could not reconcile the observed YORP strength unless the asteroid's center of mass is shifted by about 21 m along its long axis. This suggests Itokawa has two components with different densities that merged, either from a
The ASTRODEEP Frontier Fields catalogues II. Photometric redshifts and rest f...Sérgio Sacani
This document describes a public release of photometric redshifts and galaxy properties from multi-wavelength data in the Abell-2744 and MACS-J0416 galaxy cluster fields observed as part of the Frontier Fields program. Photometric redshifts were estimated using six different methods and have an accuracy of 3-5%. Accounting for gravitational lensing magnification, the H-band number counts agree with CANDELS at bright magnitudes but extend to intrinsically fainter galaxies of H=32-33. The Frontier Fields data allow probing galaxy stellar masses 0.5-1.5 dex lower than in wide fields, including sources with masses of 107-108 solar masses at z>5. Star formation rates can be detected 1
IOSR Journal of Applied Physics (IOSR-JAP) is an open access international journal that provides rapid publication (within a month) of articles in all areas of physics and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in applied physics. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
1) Researchers observed 15 transits of the exoplanet GJ 1214b using the Hubble Space Telescope to measure its transmission spectrum from 1.1 to 1.7 microns.
2) The transmission spectrum was featureless, inconsistent with cloud-free atmospheres dominated by water, methane, carbon monoxide, nitrogen, or carbon dioxide.
3) The most likely explanation for the featureless spectrum is the presence of high-altitude clouds in the planet's atmosphere, which block the transmission of stellar light through the lower atmosphere.
High-resolution UV/Optical/IR Imaging of Jupiter in 2016–2019Sérgio Sacani
Imaging observations of Jupiter with high spatial resolution were acquired beginning in 2016, with a cadence of 53
days to coincide with atmospheric observations of the Juno spacecraft during each perijove pass. The Wide Field
Camera 3 (WFC3) aboard the Hubble Space Telescope (HST) collected Jupiter images from 236 to 925 nm in 14
filters. The Near-Infrared Imager (NIRI) at Gemini North imaged Jovian thermal emission using a lucky-imaging
approach (co-adding the sharpest frames taken from a sequence of short exposures), using the M′ filter at 4.7 μm.
We discuss the data acquisition and processing and an archive collection that contains the processed WFC3 and
NIRI data (doi:10.17909/T94T1H). Zonal winds remain steady over time at most latitudes, but significant
evolution of the wind profile near 24°N in 2016 and near 15°S in 2017 was linked with convective superstorm
eruptions. Persistent mesoscale waves were seen throughout the 2016–2019 period. We link groups of lightning
flashes observed by the Juno team with water clouds in a large convective plume near 15°S and in cyclones near
35°N–55°N. Thermal infrared maps at the 10.8 micron wavelength obtained at the Very Large Telescope show
consistent high brightness temperature anomalies, despite a diversity of aerosol properties seen in the HST data.
Both WFC3 and NIRI imaging reveal depleted aerosols consistent with downwelling around the periphery of the
15°S storm, which was also observed by the Atacama Large Millimeter/submillimeter Array. NIRI imaging of
the Great Red Spot shows that locally reduced cloud opacity is responsible for dark features within the vortex. The
HST data maps multiple concentric polar hoods of high-latitude hazes.
A highly magnetized twin-jet base pinpoints a supermassive black holeSérgio Sacani
Supermassive black holes (SMBH) are essential for the production of jets in radio-loud active galactic nuclei (AGN). Theoretical
models based on (Blandford & Znajek 1977, MNRAS, 179, 433) extract the rotational energy from a Kerr black hole, which could
be the case for NGC1052, to launch these jets. This requires magnetic fields on the order of 103 G to 104 G. We imaged the vicinity
of the SMBH of the AGN NGC1052 with the Global Millimetre VLBI Array and found a bright and compact central feature that is
smaller than 1.9 light days (100 Schwarzschild radii) in radius. Interpreting this as a blend of the unresolved jet bases, we derive the
magnetic field at 1 Schwarzschild radius to lie between 200 G and 8:3 104 G consistent with Blandford & Znajek models.
Far infrared dust_temperatures_and_column_densities_of_the_malt90_molecular_c...Sérgio Sacani
Estrelas como o Sol começam suas vidas como núcleos densos e frios de gás e poeira que colapsam sob a influência da gravidade até que a fusão possa iniciar. Esses núcleos contêm de centenas a milhares de vezes a massa do Sol de material e têm uma densidade de gás mil vezes maior do que as regiões interestelares típicas (o valor típico é de uma molécula por centímetro cúbico). Como o processo de colapso ocorre nesses núcleos é algo pouco entendido, desde o número de estrelas que se formam, até os fatores que determinam suas massas, bem como a escala de tempo detalhada para o nascimento de uma estrela. O material, por exemplo, pode simplesmente cair livremente para o centro do núcleo, mas em cenários mais realistas, a queda é inibida pel pressão do gás aquecido, dos movimentos tubulentos, os campos magnéticos, ou alguma combinação desses fatores.
Os astrônomos estão estudando ativamente essas questões, observando jovens estrelas no processo de nascimento. A poeira nesses núcleos natais (ou aglomerados), contudo, faz com que o material seja opaco para a luz óptica, necessitando de observações em outros comprimentos de onda, em particular no infravermelho, submilimétrico, e rádio. nos estágios iniciais da formação das estrelas, uma estrela embrionária aquece a nuvem de poeira ao redor a temperaturas entre 10 e 30 graus Kelvin, antes que os ventos estelares e a radiação, sopre o material para longe expondo a estrela recém-nascida. Os astrônomos do CfA Andres Guzman e Howard Smith, junto com seus colegas, completaram uma análise de 3246 núcleos de formação de estrelas, a maior amostragem já feita. Os núcleos frios foram descobertos com o Submillmetre-Wavelength Sky Survey APEX, e então observados em 16 linhas espectrais submilimétricas, a informação espectral permitiu que os astrônomos pudessem determinar a distância para cada núcleo, bem como pesquisar a química e os movimentos internos do gás. O novo artigo, combina esses resultados com medidas do infravermelho distante feitas pelo Observatório Espacial Herschel da ESA. Os dados do Herschel permitiram que os cientistas calculassem a densidade da poeira, a massa e a temperatura de cada núcleo, o grande conjunto de dados então permitiu comparações estatísticas úteis entre os núcleos com vários parâmetros.
Serendipitous discovery of an extended xray jet without a radio counterpart i...Sérgio Sacani
A recent Chandra observation of the nearby galaxy cluster Abell 585 has led to the discovery of
an extended X-ray jet associated with the high-redshift background quasar B3 0727+409, a luminous
radio source at redshift z = 2:5. This is one of only few examples of high-redshift X-ray jets known
to date. It has a clear extension of about 1200, corresponding to a projected length of 100 kpc, with
a possible hot spot located 3500 from the quasar. The archival high resolution VLA maps surprisingly
reveal no extended jet emission, except for one knot about 1:400 from the quasar. The high X-ray to
radio luminosity ratio for this source appears consistent with the / (1 + z)4 amplication expected
from the inverse Compton radiative model. This serendipitous discovery may signal the existence
of an entire population of similar systems with bright X-ray and faint radio jets at high redshift, a
selection bias which must be accounted for when drawing any conclusions about the redshift evolution
of jet properties and indeed about the cosmological evolution of supermassive black holes and active
galactic nuclei in general.
A wide and collimated radio jet in 3C84 on the scale of a few hundred gravita...Sérgio Sacani
This document summarizes key findings from a study of the radio jet in galaxy 3C84 using very long baseline interferometry (VLBI) with the RadioAstron space telescope. The observations resolve the edge-brightened jet structure only 30 microarcseconds from the core, corresponding to ~350 gravitational radii. This is 10 times closer to the central engine than previous ground-based observations. The measurements show the jet has an initially wide opening angle of 130 degrees that rapidly collimates into an almost cylindrical profile out to ~8,000 gravitational radii. The wide jet observed so close to the core poses challenges for models where the jet originates from the black hole ergosphere.
Evidence for a_distant_giant_planet_in_the_solar_systemSérgio Sacani
A descoberta de um novo planeta, atualmente não é uma manchete que chama tanto assim a atenção das pessoas. Muito disso, graças ao Telescópio Espacial Kepler, que já descobriu quase 2000 exoplanetas e todo instante uma nova descoberta é anunciada, certo? Mais ou menos, a descoberta anunciada hoje, dia 20 de Janeiro de 2016, é um pouco diferente, pois não se trata de um exoplaneta, e sim de um novo planeta no Sistema Solar, e esse é um fato que intriga os astrônomos a muitos e muitos anos.
Porém, temos que ir com calma com esses anúncios. No artigo aceito para publicação no The Astronomical Journal (artigo no final do post), os autores, Mike Brown e Konstantin Batygin, do Instituto de Tecnologia da Califórnia, apresentaram o que eles dizem ser evidências circunstâncias fortes para a existência de um grande planeta ainda não descoberto, talvez, com uma massa 10 vezes a massa da Terra, orbitando os confins do nosso Sistema Solar, muito além da órbita de Plutão. Os cientistas inferiram sua presença, por meio de anomalias encontradas nas órbitas de seis objetos do chamado Cinturão de Kuiper.
O objeto, que os pesquisadores estão chamando de Planeta Nove, não chega muito perto do Sol, no ponto mais próximo da sua órbita ele fica a 30.5 bilhões de quilômetros, ou seja, cinco vezes a distância entre o Sol e Plutão. Apesar do seu grande tamanho, ele é muito apagado, e por isso ninguém até o momento conseguiu observá-lo.
Não existe ainda uma confirmação observacional da descoberta, mas as evidências são tão fortes que fizeram com que outros especialistas como Chad Trujilo do Observatório Gemini no Havaí e David Nesvorny, do Southwest Research Institute em Boulder no Colorado, ficassem impressionados e bem convencidos de que deve mesmo haver um grande planeta nas fronteiras da nossa vizinhança cósmica.
PROBING FOR EVIDENCE OF PLUMES ON EUROPA WITH HST/STISSérgio Sacani
Roth et al. (2014a) reported evidence for plumes of water venting from a southern high latitude
region on Europa – spectroscopic detection of off-limb line emission from the dissociation
products of water. Here, we present Hubble Space Telescope (HST) direct images of Europa in
the far ultraviolet (FUV) as it transited the smooth face of Jupiter, in order to measure absorption
from gas or aerosols beyond the Europa limb. Out of ten observations we found three in which
plume activity could be implicated. Two show statistically significant features at latitudes similar
to Roth et al., and the third, at a more equatorial location. We consider potential systematic
effects that might influence the statistical analysis and create artifacts, and are unable to find any
that can definitively explain the features, although there are reasons to be cautious. If the
apparent absorption features are real, the magnitude of implied outgassing is similar to that of the
Roth et al. feature, however the apparent activity appears more frequently in our data.
This document describes observations of the Seyfert 1 galaxy Mrk 509 using the Cosmic Origins Spectrograph (COS) on the Hubble Space Telescope (HST). The observations detected absorption features in the ultraviolet spectrum, which are attributed to outflowing gas from the active galactic nucleus as well as gas in the galaxy's interstellar medium and halo. The COS observations provide higher signal-to-noise and resolution than previous observations, detecting additional complexity in the absorption features. Variability in some features constrains the distances of absorbing gas components to be less than 250 pc and 1.5 kpc from the active nucleus. The absorption lines only partially cover the emission from the active nucleus, possibly due to
The large-scale nebular pattern of a superwind binary in an eccentric orbitSérgio Sacani
Preplanetary nebulae and planetary nebulae are evolved,
mass-losing stellar objects that show a wide variety of morphologies.
Many of these nebulae consist of outer structures
that are nearly spherical (spiral/shell/arc/halo) and inner
structures that are highly asymmetric (bipolar/multipolar)1,2.
The coexistence of such geometrically distinct structures is
enigmatic because it hints at the simultaneous presence of
both wide and close binary interactions, a phenomenon that
has been attributed to stellar binary systems with eccentric
orbits3. Here, we report high-resolution molecular line observations
of the circumstellar spiral-shell pattern of AFGL 3068,
an asymptotic giant branch star transitioning to the preplanetary
nebula phase. The observations clearly reveal that the
dynamics of the mass loss is influenced by the presence of an
eccentric-orbit binary. This quintessential object opens a window
on the nature of deeply embedded binary stars through
the circumstellar spiral-shell patterns that reside at distances
of several thousand au from the stars.
This document is the table of contents and introduction for a science fair project analyzing solar p-mode travel times measured using sodium and potassium spectra. The student took images of the sun using these two spectra, which correspond to different solar altitudes. Power spectra were generated and trumpet structures were compared by fitting circles to cross-sections. Radius vs. frequency plots showed the sodium radii were generally larger. While this provides evidence against the hypothesis that travel times are the same, more data is needed for a definitive conclusion on whether p-waves are fully evanescent.
Small scatter and_nearly_isothermal_mass_profiles_to_four_half_light_radii_fr...Sérgio Sacani
This document summarizes the results of a study analyzing the total mass density profiles of 14 early-type galaxies using two-dimensional stellar kinematic data out to large radii of 2-6 half-light radii. The study finds that the total density profiles are well described by a nearly-isothermal power law with density proportional to radius from 0.1 to at least 4 half-light radii. The average logarithmic slope is -2.19 with a small scatter of only 0.11. This places tight constraints on galaxy formation models and illustrates the power of extended two-dimensional stellar kinematic observations.
Dust in the_polar_region_as_a_major_contributor_to_the_infrared_emission_of_a...Sérgio Sacani
The mid-infrared emission of the active galactic nucleus NGC 3783 was observed using interferometry over multiple epochs, providing dense coverage of position angles and baselines. The emission was found to be strongly elongated along a position angle of -52 degrees, closely aligned with the polar axis orientation of -45 degrees. The half-light radii were measured to be 20.0 mas by 6.7 mas, corresponding to an axis ratio of 3:1. This implies that 60-90% of the 8-13 micron emission is from the polar-elongated component. The observations support a scenario where the majority of mid-infrared emission in Seyfert galaxies originates from a dusty wind in the polar region,
3C 273 was one of the first quasars discovered in 1963. It remains one of the brightest and best studied quasars. It is located approximately 3 billion light years from Earth and radiates energy equivalent to 1014 times the luminosity of the Sun. 3C 273 plays a key role in understanding the nature of quasars as powered by accretion disks around supermassive black holes. It continues to be intensely observed across the electromagnetic spectrum to better understand the physics occurring in these energetic and distant cosmic objects.
One tenth solar_abundances_along_the_body_of-the_streamSérgio Sacani
This document summarizes a study that analyzed spectra from four background quasars to measure the chemical abundances along the Magellanic Stream. Two key findings are:
1) The sightlines toward RBS 144 and NGC 7714 yielded metallicities of around 0.1 times the solar value, indicating a uniform low abundance along the main body of the Stream. This supports models where the Stream was stripped from the SMC around 1-2.5 billion years ago when the SMC had a metallicity of around 0.1 solar.
2) A higher metallicity of around 0.5 solar was found in the inner Stream toward Fairall 9, sampling a filament traced to the LMC. This shows the bifurc
Imaging of the_co_snow_line_in_a_solar_nebula_analogSérgio Sacani
This document summarizes research on observing the location of the carbon monoxide (CO) snow line in protoplanetary disks. Key points:
1) N2H+ emission is expected to trace the CO snow line as N2H+ forms most abundantly in gas where CO is frozen onto dust grains.
2) Observations of the protoplanetary disk around the young star TW Hya using ALMA revealed a ring-shaped distribution of N2H+ emission with an inner radius of 21-32 AU, indicating the location of the CO snow line.
3) Disk models suggest the N2H+ emission inner edge corresponds to a midplane temperature of 16-20K,
The colision between_the_milky_way_and_andromedaSérgio Sacani
The document summarizes a simulation of the future collision between the Milky Way and Andromeda galaxies. It finds that given current observational constraints on their distance, velocity, and masses:
1) The Milky Way and Andromeda are likely to collide in a few billion years, within the lifetime of the Sun.
2) During the interaction, there is a chance the Sun could be pulled into an extended tidal tail between the galaxies.
3) Eventually, after the merger is complete, the Sun would most likely be scattered to the outer halo of the merged galaxy at a distance over 30 kpc.
This document summarizes new results from a study of proper motions in the optical jet of the galaxy M87 using over 13 years of Hubble Space Telescope imaging data. Key findings include:
1) Superluminal velocities (above the speed of light) were measured for knots as far out as knot C in the jet, suggesting these speeds persist over large distances.
2) Significant apparent accelerations both parallel and transverse to the jet axis were found, as well as evidence for stationary features in some knots.
3) Complex motions including differing velocities between nearby features and changes in velocity over time were observed throughout the jet, placing constraints on theoretical jet models.
A dynamical signature_of_multiple_stellar_populations_in_47_tucanaeSérgio Sacani
The document analyzes proper motion data from Hubble Space Telescope images of the globular cluster 47 Tucanae taken over 10 years. It finds differing proper motion anisotropies between the bluest and reddest main sequence stars in 47 Tucanae, suggesting different kinematic properties for the different stellar populations. The bluest stars also exhibit the strongest central concentration. These results provide dynamical evidence for multiple stellar populations in 47 Tucanae and implications for their formation scenarios.
Evidence for a_complex_enrichment_history_of_the_stream_from_fairall_9_sightlineSérgio Sacani
This study analyzes absorption spectra of the Magellanic Stream (MS) toward the quasar Fairall 9, obtained using the Hubble Space Telescope Cosmic Origins Spectrograph (HST/COS) and the Very Large Telescope Ultraviolet and Visible Echelle Spectrograph (VLT/UVES). The spectra reveal absorption from multiple velocity components of the MS, indicating multiphase gas. Surprisingly, the sulfur abundance is found to be high ([S/H] = -0.30), five times higher than other MS sightlines, while the nitrogen abundance is lower ([N/H] = -1.15). This points to a complex enrichment history, where the gas toward Fair
Grb 130606a as_a_probe_of_the_intergalactic_medium_and_the_interstelar_medium...Sérgio Sacani
This document summarizes observations of the gamma-ray burst GRB 130606A at a redshift of z=5.913 using spectroscopy from the MMT and Gemini telescopes. The high quality spectra exhibit a smooth near-infrared continuum that is sharply cut off by Lyman-alpha absorption at z=5.91, with some flux transmitted through the Lyman-alpha forest at lower redshifts. Metal absorption lines in the host galaxy are used to constrain its metallicity between -1.7 and -0.5 solar. Transmission in the Lyman-alpha forest is found to evolve consistently with previous quasar observations. An extended region at z=5.77 shows no Lyman-alpha transmission,
Mass and motion_of_globulettes_in_the_rosette_nebulaSérgio Sacani
This document summarizes observations of globulettes (small molecular clumps) in the Rosette Nebula made using radio telescopes and infrared imaging. Radio observations of 16 globulettes detected molecular line emission from 12CO and 13CO, allowing masses to be estimated. Masses ranged from about 50 to 500 Jupiter masses. Infrared imaging found that several globulettes are very opaque and contain dense cores. Analysis of velocities found that globulettes and other nebula structures are expanding at about 22 km/s, with globulettes having only small velocity differences, suggesting they are moving with the general expansion. Some globulettes appear to be detaching from larger structures as they expand outwards.
Allan Sandage devoted significant research efforts to determining the Hubble constant and calibrating the cosmic distance scale. In the 1950s, his work confirmed Baade's revision that galaxy distances were twice as large as previously thought. Over the following decades, through calibrating different distance indicators like Cepheid variables and tip of the red giant branch stars, Sandage lowered his estimate of the Hubble constant from 250 km/s/Mpc to around 60 km/s/Mpc. His landmark "Steps toward the Hubble Constant" series in the 1970s utilized galaxy properties to extend the distance scale and further refine the Hubble constant value.
The identification of_93_day_periodic_photometric_variability_for_yso_ylw_16aSérgio Sacani
This study identifies a 93 day periodic photometric variability in the Class I young stellar object (YSO) YLW 16A in the Rho Ophiuchus star forming region. Light curve analysis reveals variations of ~0.5 magnitudes in the Ks band over this period. The authors propose a triple system model consisting of an inner binary with a 93 day period eclipsed by a warped circumbinary disk, with a tertiary companion at ~40 AU responsible for warping the disk. This model is similar to one previously proposed for another YSO, WL 4, and may indicate such triple systems with eclipsing disks are common around young stars. Understanding these systems can provide insights into stellar and planetary formation and evolution.
The stelar mass_growth_of_brightest_cluster_galaxies_in_the_irac_shallow_clus...Sérgio Sacani
This document describes a study of the stellar mass growth of brightest cluster galaxies (BCGs) between z=1.5 and z=0.5 using data from the Spitzer IRAC Shallow Cluster Survey (ISCS). The researchers developed a method to select high-redshift clusters as progenitors of lower-redshift clusters to study the evolution of BCG stellar masses. They find that between z=1.5 and z=0.5, the BCGs grew in stellar mass by a factor of 2.3, matching predictions from a semi-analytic galaxy formation model. Below z=0.5, there are hints of differences between the observed BCG growth and the model predictions.
A dwarf galaxy is colliding with the large spiral galaxy NGC 1232, as revealed by X-ray observations from Chandra. The collision is creating a large region (7.25 kpc in diameter) of shocked, hot gas with a temperature of around 5.8 million kelvin. The X-ray luminosity of this collisional aftermath is estimated to be 3.7x10^38 ergs/s. Based on the size and temperature of the X-ray emitting region, the collision likely involves a dwarf galaxy and represents a massive energy input into NGC 1232, far exceeding a typical supernova. Such collisions detected solely in X-rays may provide insights into the role of dwarf galaxy interactions in the evolution of
Abundance and isotopic_composition_of_gases_in_the_martian_atmosphere_from_th...Sérgio Sacani
The Curiosity rover measured the composition and isotopic ratios of gases in the Martian atmosphere using its Sample Analysis at Mars (SAM) instrument suite. Key findings include:
- Carbon dioxide makes up 96% of the atmosphere.
- Argon-40 and nitrogen levels are consistent with previous Viking measurements, but the 40Ar/36Ar ratio is lower and the 40Ar/N2 ratio is higher than Viking.
- Isotopic signatures of carbon and other gases support the hypothesis that Mars has lost a significant portion of its original atmosphere over geological time through atmospheric escape processes.
Candels the correlation_between_galaxy_morphology_and_star_formation_activity...Sérgio Sacani
This document summarizes a study investigating the relationship between galaxy morphology and star formation activity at z ~ 2 using a sample of 1,671 galaxies from CANDELS images in the GOODS-South field. The sample separates into massive, red, passive galaxies and less massive, blue, star-forming galaxies, correlating well with morphological properties. Star-forming galaxies show a variety of morphologies including clumpy structures and bulges mixed with faint disks, while passive galaxies often have compact morphologies resembling local spheroids. Similar trends are seen in local massive galaxies, suggesting the Hubble sequence was in place by z ~ 2.
This document summarizes observations of the gas cloud G2 as it passes near the supermassive black hole at the center of the Milky Way galaxy. New observations in 2013 with the NACO and SINFONI instruments on the VLT show that G2 continues to be stretched out along its orbit due to tidal forces. The head of G2 is now stretched over 15,000 Schwarzschild radii. Some gas has passed the pericenter of the orbit and is seen blueshifted. The luminosity and line ratios of G2 remain constant, showing no evidence of heating as it interacts with ambient gas. The pericenter passage will occur over about a year as G2 is stretched out along its orbit.
Effect of a_high_opacity_on_the_light_curves_of_radioactively_powered_transie...Sérgio Sacani
This document discusses how higher opacities from lanthanide elements in the ejecta of neutron star mergers could dramatically affect the predicted light curves of electromagnetic counterparts. The key points are:
1) Ab initio calculations show r-process element opacities are orders of magnitude higher than previously assumed iron opacities, particularly from lanthanide elements.
2) With these higher opacities, radiation transport models predict light curves that are longer (lasting about a week), dimmer, and redder, with emission peaked in the infrared rather than optical/ultraviolet.
3) A two-component light curve may result if there is both lanthanide-rich ejecta and a secondary
The document reports measurements of isotope ratios in CO2 and H2O in the Martian atmosphere taken by the Curiosity rover. Isotope ratios of hydrogen, carbon, and oxygen can reveal information about planetary processes like atmospheric loss and interactions with the surface. The measurements imply that the Martian reservoirs of CO2 and H2O were largely established 4 billion years ago, but that some atmospheric loss or surface interaction may still be ongoing. Comparison to measurements of Martian meteorites provides information about these long-term planetary processes and the evolution of the Martian atmosphere and surface.
The document summarizes new HI observations of Hoag's Object obtained with the Westerbork Synthesis Radio Telescope. The key findings are:
1) The HI is detected in a ring that coincides with and extends beyond the optical ring of Hoag's Object. The entire HI structure is twice as large as the optical ring and shows a mild warp in its outer regions.
2) The HI kinematics are regular with no disturbances, providing evidence against a recent interaction being the source of the HI.
3) Two additional faint HI sources are detected near Hoag's Object, approximately 0.3 and 1 Mpc away in projected distance. At least one does
ALMA Observations of the Extraordinary Carina Pillars: A Complementary SampleSérgio Sacani
We present a study of six dusty and gaseous pillars (containing the HH 1004 and HH 1010 objects)
and globules (that contain the HH 666, HH 900, HH 1006, and HH 1066 objects) localized in the Carina
nebula using sensitive and high angular resolution (∼0.3′′) Atacama Large Millimeter/Sub-millimeter
Array (ALMA) observations. This is a more extensive study that the one presented in Cortes-Rangel
et al. (2020). As in this former study, we also analyzed the 1.3 mm continuum emission and C18O(2−1),
N2D+(3−2) and 12CO(2−1) spectral lines. These new observations revealed the molecular outflows
emanating from the pillars, the dusty envelopes+disks that are exciting them, and the extended HH
objects far from their respective pillars. We reveal that the masses of the disks+envelopes are in a
range of 0.02 to 0.38 M⊙, and those for the molecular outflows are of the order of 10−3 M⊙, which
suggests that their exciting sources might be low- or intermediate-mass protostars as already revealed
in recent studies at infrared and submillimeter bands. In the regions associated with the objects HH
900 and HH 1004, we report multiple millimeter continuum sources, from where several molecular
outflows emanate.
MUSE sneaks a peek at extreme ram-pressure stripping events. I. A kinematic s...Sérgio Sacani
- MUSE observations of the galaxy ESO137-001 reveal an extended gaseous tail over 30 kpc long traced by H-alpha emission, providing evidence of an extreme ram pressure stripping event as the galaxy falls into the massive Norma galaxy cluster.
- Analysis of the H-alpha kinematics and stellar velocity field show that ram pressure has removed the interstellar medium from the outer disk while the primary tail is still fed by gas from the galaxy center, with gravitational interactions not appearing to be the main mechanism of gas removal.
- The stripped gas retains evidence of the disk's rotational velocity out to around 20 kpc downstream, indicating the galaxy is moving radially along the plane of the sky, while
This document describes observations of the galaxy ESO137-001 using the MUSE instrument on the VLT. The key points are:
1) MUSE observations reveal an extended gas tail stretching over 30 kpc from the galaxy, tracing ongoing ram pressure stripping as it falls into the Norma galaxy cluster.
2) Analysis of the gas kinematics and stellar velocity field show that ram pressure has removed the interstellar medium from the outer disk while the primary tail is still fed by gas from the galaxy center.
3) The stripped gas retains evidence of the disk's rotational velocity out to 20 kpc downstream, indicating the galaxy is moving radially through the cluster. Beyond this the gas shows greater turbulence,
Counterjet infrared symmetry of hh 34 and the size of the jet formation regionSérgio Sacani
The document summarizes new Spitzer IRAC images of the HH 34 outflow that detect both the southern jet and northern counterjet with comparable intensities and surprising symmetry. This removes the problem of apparent asymmetry close to the source versus large-scale symmetry. Quantitative analysis shows the counterjet knots are positioned symmetrically to within 0.11-1.57 pixels of the corresponding jet knots. This degree of symmetry implies the jet production region has a characteristic size less than 2.8 AU, providing the strongest constraint yet on the size of the region producing HH jets.
Triple Spiral Arms of a Triple Protostar System Imaged in Molecular LinesSérgio Sacani
Most stars form in multiple-star systems. For a better understanding of their formation processes, it is important to
resolve the individual protostellar components and the surrounding envelope and disk material at the earliest
possible formation epoch, because the formation history can be lost in a few orbital timescales. Here we present
Atacama Large Millimeter/submillimeter Array observational results of a young multiple protostellar system,
IRAS 04239+2436, where three well-developed large spiral arms were detected in the shocked SO emission.
Along the most conspicuous arm, the accretion streamer was also detected in the SO2 emission. The observational
results are complemented by numerical magnetohydrodynamic simulations, where those large arms only appear in
magnetically weakened clouds. Numerical simulations also suggest that the large triple spiral arms are the result of
gravitational interactions between compact triple protostars and the turbulent infalling envelope.
X-rays from a Central “Exhaust Vent” of the Galactic Center ChimneySérgio Sacani
Using deep archival observations from the Chandra X-ray Observatory, we present an analysis of
linear X-ray-emitting features located within the southern portion of the Galactic center chimney,
and oriented orthogonal to the Galactic plane, centered at coordinates l = 0.08◦
, b = −1.42◦
. The
surface brightness and hardness ratio patterns are suggestive of a cylindrical morphology which may
have been produced by a plasma outflow channel extending from the Galactic center. Our fits of the
feature’s spectra favor a complex two-component model consisting of thermal and recombining plasma
components, possibly a sign of shock compression or heating of the interstellar medium by outflowing
material. Assuming a recombining plasma scenario, we further estimate the cooling timescale of this
plasma to be on the order of a few hundred to thousands of years, leading us to speculate that a
sequence of accretion events onto the Galactic Black Hole may be a plausible quasi-continuous energy
source to sustain the observed morphology
Solving the Multimessenger Puzzle of the AGN-starburst Composite Galaxy NGC 1068Sérgio Sacani
Multiwavelength observations indicate that some starburst galaxies show a dominant nonthermal contribution from
their central region. These active galactic nuclei (AGN)-starburst composites are of special interest, as both
phenomena on their own are potential sources of highly energetic cosmic rays and associated γ-ray and neutrino
emission. In this work, a homogeneous, steady-state two-zone multimessenger model of the nonthermal emission
from the AGN corona as well as the circumnuclear starburst region is developed and subsequently applied to the
case of NGC 1068, which has recently shown some first indications of high-energy neutrino emission. Here, we
show that the entire spectrum of multimessenger data—from radio to γ-rays including the neutrino constraint—can
be described very well if both, starburst and AGN corona, are taken into account. Using only a single emission
region is not sufficient.
Jet reorientation in central galaxies of clusters and groups: insights from V...Sérgio Sacani
Recent observations of galaxy clusters and groups with misalignments between their central AGN jets
and X-ray cavities, or with multiple misaligned cavities, have raised concerns about the jet – bubble
connection in cooling cores, and the processes responsible for jet realignment. To investigate the
frequency and causes of such misalignments, we construct a sample of 16 cool core galaxy clusters and
groups. Using VLBA radio data we measure the parsec-scale position angle of the jets, and compare
it with the position angle of the X-ray cavities detected in Chandra data. Using the overall sample
and selected subsets, we consistently find that there is a 30% – 38% chance to find a misalignment
larger than ∆Ψ = 45◦ when observing a cluster/group with a detected jet and at least one cavity. We
determine that projection may account for an apparently large ∆Ψ only in a fraction of objects (∼35%),
and given that gas dynamical disturbances (as sloshing) are found in both aligned and misaligned
systems, we exclude environmental perturbation as the main driver of cavity – jet misalignment.
Moreover, we find that large misalignments (up to ∼ 90◦
) are favored over smaller ones (45◦ ≤ ∆Ψ ≤
70◦
), and that the change in jet direction can occur on timescales between one and a few tens of Myr.
We conclude that misalignments are more likely related to actual reorientation of the jet axis, and we
discuss several engine-based mechanisms that may cause these dramatic changes.
Dust-trapping Vortices and a Potentially Planet-triggered Spiral Wake in the ...Sérgio Sacani
The radial drift problem constitutes one of the most fundamental problems in planet formation theory, as it predicts
particles to drift into the star before they are able to grow to planetesimal size. Dust-trapping vortices have been
proposed as a possible solution to this problem, as they might be able to trap particles over millions of years,
allowing them to grow beyond the radial drift barrier. Here, we present ALMA 0 04 resolution imaging of the pretransitional
disk of V1247 Orionis that reveals an asymmetric ring as well as a sharply confined crescent structure,
resembling morphologies seen in theoretical models of vortex formation. The asymmetric ring (at 0 17 = 54 au
separation from the star) and the crescent (at 0 38 = 120 au) seem smoothly connected through a one-armed
spiral-arm structure that has been found previously in scattered light. We propose a physical scenario with a planet
orbiting at ∼0 3 ≈ 100 au, where the one-armed spiral arm detected in polarized light traces the accretion stream
feeding the protoplanet. The dynamical influence of the planet clears the gap between the ring and the crescent and
triggers two vortices that trap millimeter-sized particles, namely, the crescent and the bright asymmetry seen in the
ring. We conducted dedicated hydrodynamics simulations of a disk with an embedded planet, which results in
similar spiral-arm morphologies as seen in our scattered-light images. At the position of the spiral wake and the
crescent we also observe 12CO(3-2) and H12CO+ (4-3) excess line emission, likely tracing the increased scaleheight
in these disk regions.
This document summarizes an infrared survey of the massive star forming region RCW 57 (NGC 3576) using L-band (3.5 μm) data from SPIREX and JHKs data from 2MASS. Over 50% of the 209 sources detected showed infrared excess, indicating circumstellar disks. Comparison to other surveys supports a very high initial disk fraction (>80%) around massive stars, though disks may dissipate faster around high-mass stars. 33 sources only detected at L-band indicate heavily embedded, massive Class I protostars. Diffuse PAH emission was also detected throughout RCW 57.
Fleeting Small-scale Surface Magnetic Fields Build the Quiet-Sun CoronaSérgio Sacani
Arch-like loop structures filled with million Kelvin hot plasma form the building blocks of the quiet-Sun corona.
Both high-resolution observations and magnetoconvection simulations show the ubiquitous presence of magnetic
fields on the solar surface on small spatial scales of ∼100 km. However, the question of how exactly these quietSun coronal loops originate from the photosphere and how the magnetic energy from the surface is channeled to
heat the overlying atmosphere is a long-standing puzzle. Here we report high-resolution photospheric magnetic
field and coronal data acquired during the second science perihelion of Solar Orbiter that reveal a highly dynamic
magnetic landscape underlying the observed quiet-Sun corona. We found that coronal loops often connect to
surface regions that harbor fleeting weaker, mixed-polarity magnetic field patches structured on small spatial
scales, and that coronal disturbances could emerge from these areas. We suggest that weaker magnetic fields with
fluxes as low as 1015 Mx and/or those that evolve on timescales less than 5 minutes are crucial to understanding
the coronal structuring and dynamics.
The herschel view_of_massive_star_formation_in_dense_and_cold_filament_w48Sérgio Sacani
The Herschel Space Observatory observed the IRDC filament G035.39–00.33 in the W48 molecular cloud complex. The observations revealed 28 compact dense cores, 13 of which have masses greater than 20 solar masses. These massive dense cores are excellent candidates to form intermediate- to high-mass stars. Most of the massive dense cores are located within the G035.39–00.33 filament and contain infrared-quiet high-mass protostars. The large number of protostars suggests a "mini-burst" of star formation is occurring within the filament, with an efficiency of about 15% and a formation rate of around 40 solar masses per year per square kiloparsec. Some extended Si
Magnetic fields and relativistic electrons fill entire galaxy clusterSérgio Sacani
- The authors analyzed deep LOFAR radio observations of the galaxy cluster Abell 2255, detecting radio synchrotron emission distributed over an unprecedented scale of at least 5 megaparsecs, well beyond the cluster outskirts.
- This pervasive radio emission indicates that shocks and turbulence efficiently transfer kinetic energy into relativistic particles and magnetic fields throughout the cluster, including the periphery.
- The strength of the emission requires magnetic field energy densities at least 100 times higher than expected from simple compression of primordial fields, suggesting efficient dynamo action even in the cluster outskirts.
The Expansion of the X-Ray Nebula Around η CarSérgio Sacani
1. The author analyzes over 20 years of Chandra X-ray images to measure for the first time the expansion of the X-ray nebula around η Carinae.
2. A combined Chandra image reveals a faint, nearly uniform elliptical shell surrounding the X-ray bright ring, with a similar orientation and shape as the Homunculus nebula but about 3 times larger.
3. The author measures proper motions of brighter regions associated with the X-ray emitting ring, such as the S-ridge and W-arc. Motions are consistent with optical studies of ejecta from the 1840s Great Eruption.
Large scale mass_distribution_in_the_illustris_simulationSérgio Sacani
Observations at low redshifts thus far fail to account for all of the baryons expected in the
Universe according to cosmological constraints. A large fraction of the baryons presumably
resides in a thin and warm–hot medium between the galaxies, where they are difficult to observe
due to their low densities and high temperatures. Cosmological simulations of structure
formation can be used to verify this picture and provide quantitative predictions for the distribution
of mass in different large-scale structure components. Here we study the distribution
of baryons and dark matter at different epochs using data from the Illustris simulation. We
identify regions of different dark matter density with the primary constituents of large-scale
structure, allowing us to measure mass and volume of haloes, filaments and voids. At redshift
zero, we find that 49 per cent of the dark matter and 23 per cent of the baryons are within
haloes more massive than the resolution limit of 2 × 108 M⊙. The filaments of the cosmic
web host a further 45 per cent of the dark matter and 46 per cent of the baryons. The remaining
31 per cent of the baryons reside in voids. The majority of these baryons have been transported
there through active galactic nuclei feedback. We note that the feedback model of Illustris
is too strong for heavy haloes, therefore it is likely that we are overestimating this amount.
Categorizing the baryons according to their density and temperature, we find that 17.8 per cent
of them are in a condensed state, 21.6 per cent are present as cold, diffuse gas, and 53.9 per cent
are found in the state of a warm–hot intergalactic medium.
This document summarizes a survey of the massive star forming region RCW 57 (NGC 3576) using JHKs and L-band (3.5 μm) infrared data. Over 50% of the sources detected showed infrared excess emission, indicating the presence of circumstellar disks. Comparison to other regions supported a very high initial disk fraction (>80%) around massive stars, though disks may dissipate faster around high-mass stars. 33 sources only detected at L-band indicated heavily embedded, massive Class I protostars. Diffuse polycyclic aromatic hydrocarbon emission was also detected throughout the region.
Galaxy growth in a massive halo in the first billion years of cosmic historySérgio Sacani
According to the current understanding of cosmic structure formation, the precursors of the most massive structures in the Universe began to form shortly after the Big Bang, in regions corresponding to the largest fluctuations in the cosmic density field1–3. Observing these structures during their period of active growth and assembly—the first few hundred million years of the Universe—is challenging because it requires surveys that are sensitive enough to detect the distant galaxies that act as signposts for these structures and wide enough to capture the rarest objects. As a result, very few such objects have been detected so far4,5. Here we report observations of a far-infrared-luminous object at redshift 6.900 (less than 800 million years after the Big Bang) that was discovered in a wide-field survey6. High-resolution imaging shows it to be a pair of extremely massive star-forming galaxies. The larger is forming stars at a rate of 2,900 solar masses per year, contains 270 billion solar masses of gas and 2.5 billion solar masses of dust, and is more massive than any other known object at a redshift of more than 6. Its rapid star formation is probably triggered by its companion galaxy at a projected separation of 8 kiloparsecs. This merging companion hosts 35 billion solar masses of stars and has a star-formation rate of 540 solar masses per year, but has an order of magnitude less gas and dust than its neighbour and physical conditions akin to those observed in lower-metallicity galaxies in the nearby Universe7. These objects suggest the presence of a dark-matter halo with a mass of more than 100 billion solar masses, making it among the rarest dark-matter haloes that should exist in the Universe at this epoch.
The canarias einstein_ring_a_newly_discovered_optical_einstein_ringSérgio Sacani
This document reports the discovery of a newly discovered optical Einstein ring (ER) called the "Canarias Einstein Ring". It was discovered serendipitously in imaging data from the Dark Energy Camera. Follow-up spectroscopy with the Gran Telescopio CANARIAS confirmed the nature of the system, with the lens being an early-type galaxy at a redshift of z=0.581 and the source being a starburst galaxy at z=1.165. Analysis of the system determined the Einstein radius to be 2.16 arcseconds and the total enclosed mass producing the lensing effect to be 1.86 ± 0.23 × 1012 solar masses.
Dust production and_particle_acceleration_in_supernova_1987_a_revealed_with_almaSérgio Sacani
This document presents spatially resolved submillimeter observations of supernova remnant SN 1987A using the Atacama Large Millimeter/Submillimeter Array (ALMA). The observations reveal that at longer wavelengths (2.8 mm - 1.4 mm), the emission is from a torus associated with the supernova shock wave, while at shorter wavelengths (870 μm - 450 μm) the emission is dominated by the inner supernova ejecta. For the first time, the dust emission is unambiguously shown to originate from the inner ejecta rather than from the surrounding material, supporting theoretical models of significant dust production in supernovae. The observations also allow separation of synchrotron emission from shock-accelerated particles in
Similar to Alma observations of_the_hh46_47_molecular_outflow (20)
The binding of cosmological structures by massless topological defectsSérgio Sacani
Assuming spherical symmetry and weak field, it is shown that if one solves the Poisson equation or the Einstein field
equations sourced by a topological defect, i.e. a singularity of a very specific form, the result is a localized gravitational
field capable of driving flat rotation (i.e. Keplerian circular orbits at a constant speed for all radii) of test masses on a thin
spherical shell without any underlying mass. Moreover, a large-scale structure which exploits this solution by assembling
concentrically a number of such topological defects can establish a flat stellar or galactic rotation curve, and can also deflect
light in the same manner as an equipotential (isothermal) sphere. Thus, the need for dark matter or modified gravity theory is
mitigated, at least in part.
EWOCS-I: The catalog of X-ray sources in Westerlund 1 from the Extended Weste...Sérgio Sacani
Context. With a mass exceeding several 104 M⊙ and a rich and dense population of massive stars, supermassive young star clusters
represent the most massive star-forming environment that is dominated by the feedback from massive stars and gravitational interactions
among stars.
Aims. In this paper we present the Extended Westerlund 1 and 2 Open Clusters Survey (EWOCS) project, which aims to investigate
the influence of the starburst environment on the formation of stars and planets, and on the evolution of both low and high mass stars.
The primary targets of this project are Westerlund 1 and 2, the closest supermassive star clusters to the Sun.
Methods. The project is based primarily on recent observations conducted with the Chandra and JWST observatories. Specifically,
the Chandra survey of Westerlund 1 consists of 36 new ACIS-I observations, nearly co-pointed, for a total exposure time of 1 Msec.
Additionally, we included 8 archival Chandra/ACIS-S observations. This paper presents the resulting catalog of X-ray sources within
and around Westerlund 1. Sources were detected by combining various existing methods, and photon extraction and source validation
were carried out using the ACIS-Extract software.
Results. The EWOCS X-ray catalog comprises 5963 validated sources out of the 9420 initially provided to ACIS-Extract, reaching a
photon flux threshold of approximately 2 × 10−8 photons cm−2
s
−1
. The X-ray sources exhibit a highly concentrated spatial distribution,
with 1075 sources located within the central 1 arcmin. We have successfully detected X-ray emissions from 126 out of the 166 known
massive stars of the cluster, and we have collected over 71 000 photons from the magnetar CXO J164710.20-455217.
The debris of the ‘last major merger’ is dynamically youngSérgio Sacani
The Milky Way’s (MW) inner stellar halo contains an [Fe/H]-rich component with highly eccentric orbits, often referred to as the
‘last major merger.’ Hypotheses for the origin of this component include Gaia-Sausage/Enceladus (GSE), where the progenitor
collided with the MW proto-disc 8–11 Gyr ago, and the Virgo Radial Merger (VRM), where the progenitor collided with the
MW disc within the last 3 Gyr. These two scenarios make different predictions about observable structure in local phase space,
because the morphology of debris depends on how long it has had to phase mix. The recently identified phase-space folds in Gaia
DR3 have positive caustic velocities, making them fundamentally different than the phase-mixed chevrons found in simulations
at late times. Roughly 20 per cent of the stars in the prograde local stellar halo are associated with the observed caustics. Based
on a simple phase-mixing model, the observed number of caustics are consistent with a merger that occurred 1–2 Gyr ago.
We also compare the observed phase-space distribution to FIRE-2 Latte simulations of GSE-like mergers, using a quantitative
measurement of phase mixing (2D causticality). The observed local phase-space distribution best matches the simulated data
1–2 Gyr after collision, and certainly not later than 3 Gyr. This is further evidence that the progenitor of the ‘last major merger’
did not collide with the MW proto-disc at early times, as is thought for the GSE, but instead collided with the MW disc within
the last few Gyr, consistent with the body of work surrounding the VRM.
Observation of Io’s Resurfacing via Plume Deposition Using Ground-based Adapt...Sérgio Sacani
Since volcanic activity was first discovered on Io from Voyager images in 1979, changes
on Io’s surface have been monitored from both spacecraft and ground-based telescopes.
Here, we present the highest spatial resolution images of Io ever obtained from a groundbased telescope. These images, acquired by the SHARK-VIS instrument on the Large
Binocular Telescope, show evidence of a major resurfacing event on Io’s trailing hemisphere. When compared to the most recent spacecraft images, the SHARK-VIS images
show that a plume deposit from a powerful eruption at Pillan Patera has covered part
of the long-lived Pele plume deposit. Although this type of resurfacing event may be common on Io, few have been detected due to the rarity of spacecraft visits and the previously low spatial resolution available from Earth-based telescopes. The SHARK-VIS instrument ushers in a new era of high resolution imaging of Io’s surface using adaptive
optics at visible wavelengths.
Earliest Galaxies in the JADES Origins Field: Luminosity Function and Cosmic ...Sérgio Sacani
We characterize the earliest galaxy population in the JADES Origins Field (JOF), the deepest
imaging field observed with JWST. We make use of the ancillary Hubble optical images (5 filters
spanning 0.4−0.9µm) and novel JWST images with 14 filters spanning 0.8−5µm, including 7 mediumband filters, and reaching total exposure times of up to 46 hours per filter. We combine all our data
at > 2.3µm to construct an ultradeep image, reaching as deep as ≈ 31.4 AB mag in the stack and
30.3-31.0 AB mag (5σ, r = 0.1” circular aperture) in individual filters. We measure photometric
redshifts and use robust selection criteria to identify a sample of eight galaxy candidates at redshifts
z = 11.5 − 15. These objects show compact half-light radii of R1/2 ∼ 50 − 200pc, stellar masses of
M⋆ ∼ 107−108M⊙, and star-formation rates of SFR ∼ 0.1−1 M⊙ yr−1
. Our search finds no candidates
at 15 < z < 20, placing upper limits at these redshifts. We develop a forward modeling approach to
infer the properties of the evolving luminosity function without binning in redshift or luminosity that
marginalizes over the photometric redshift uncertainty of our candidate galaxies and incorporates the
impact of non-detections. We find a z = 12 luminosity function in good agreement with prior results,
and that the luminosity function normalization and UV luminosity density decline by a factor of ∼ 2.5
from z = 12 to z = 14. We discuss the possible implications of our results in the context of theoretical
models for evolution of the dark matter halo mass function.
THE IMPORTANCE OF MARTIAN ATMOSPHERE SAMPLE RETURN.Sérgio Sacani
The return of a sample of near-surface atmosphere from Mars would facilitate answers to several first-order science questions surrounding the formation and evolution of the planet. One of the important aspects of terrestrial planet formation in general is the role that primary atmospheres played in influencing the chemistry and structure of the planets and their antecedents. Studies of the martian atmosphere can be used to investigate the role of a primary atmosphere in its history. Atmosphere samples would also inform our understanding of the near-surface chemistry of the planet, and ultimately the prospects for life. High-precision isotopic analyses of constituent gases are needed to address these questions, requiring that the analyses are made on returned samples rather than in situ.
Multi-source connectivity as the driver of solar wind variability in the heli...Sérgio Sacani
The ambient solar wind that flls the heliosphere originates from multiple
sources in the solar corona and is highly structured. It is often described
as high-speed, relatively homogeneous, plasma streams from coronal
holes and slow-speed, highly variable, streams whose source regions are
under debate. A key goal of ESA/NASA’s Solar Orbiter mission is to identify
solar wind sources and understand what drives the complexity seen in the
heliosphere. By combining magnetic feld modelling and spectroscopic
techniques with high-resolution observations and measurements, we show
that the solar wind variability detected in situ by Solar Orbiter in March
2022 is driven by spatio-temporal changes in the magnetic connectivity to
multiple sources in the solar atmosphere. The magnetic feld footpoints
connected to the spacecraft moved from the boundaries of a coronal hole
to one active region (12961) and then across to another region (12957). This
is refected in the in situ measurements, which show the transition from fast
to highly Alfvénic then to slow solar wind that is disrupted by the arrival of
a coronal mass ejection. Our results describe solar wind variability at 0.5 au
but are applicable to near-Earth observatories.
Gliese 12 b: A Temperate Earth-sized Planet at 12 pc Ideal for Atmospheric Tr...Sérgio Sacani
Recent discoveries of Earth-sized planets transiting nearby M dwarfs have made it possible to characterize the
atmospheres of terrestrial planets via follow-up spectroscopic observations. However, the number of such planets
receiving low insolation is still small, limiting our ability to understand the diversity of the atmospheric
composition and climates of temperate terrestrial planets. We report the discovery of an Earth-sized planet
transiting the nearby (12 pc) inactive M3.0 dwarf Gliese 12 (TOI-6251) with an orbital period (Porb) of 12.76 days.
The planet, Gliese 12 b, was initially identified as a candidate with an ambiguous Porb from TESS data. We
confirmed the transit signal and Porb using ground-based photometry with MuSCAT2 and MuSCAT3, and
validated the planetary nature of the signal using high-resolution images from Gemini/NIRI and Keck/NIRC2 as
well as radial velocity (RV) measurements from the InfraRed Doppler instrument on the Subaru 8.2 m telescope
and from CARMENES on the CAHA 3.5 m telescope. X-ray observations with XMM-Newton showed the host
star is inactive, with an X-ray-to-bolometric luminosity ratio of log 5.7 L L X bol » - . Joint analysis of the light
curves and RV measurements revealed that Gliese 12 b has a radius of 0.96 ± 0.05 R⊕,a3σ mass upper limit of
3.9 M⊕, and an equilibrium temperature of 315 ± 6 K assuming zero albedo. The transmission spectroscopy metric
(TSM) value of Gliese 12 b is close to the TSM values of the TRAPPIST-1 planets, adding Gliese 12 b to the small
list of potentially terrestrial, temperate planets amenable to atmospheric characterization with JWST.
Gliese 12 b, a temperate Earth-sized planet at 12 parsecs discovered with TES...Sérgio Sacani
We report on the discovery of Gliese 12 b, the nearest transiting temperate, Earth-sized planet found to date. Gliese 12 is a
bright (V = 12.6 mag, K = 7.8 mag) metal-poor M4V star only 12.162 ± 0.005 pc away from the Solar system with one of the
lowest stellar activity levels known for M-dwarfs. A planet candidate was detected by TESS based on only 3 transits in sectors
42, 43, and 57, with an ambiguity in the orbital period due to observational gaps. We performed follow-up transit observations
with CHEOPS and ground-based photometry with MINERVA-Australis, SPECULOOS, and Purple Mountain Observatory,
as well as further TESS observations in sector 70. We statistically validate Gliese 12 b as a planet with an orbital period of
12.76144 ± 0.00006 d and a radius of 1.0 ± 0.1 R⊕, resulting in an equilibrium temperature of ∼315 K. Gliese 12 b has excellent
future prospects for precise mass measurement, which may inform how planetary internal structure is affected by the stellar
compositional environment. Gliese 12 b also represents one of the best targets to study whether Earth-like planets orbiting cool
stars can retain their atmospheres, a crucial step to advance our understanding of habitability on Earth and across the galaxy.
The importance of continents, oceans and plate tectonics for the evolution of...Sérgio Sacani
Within the uncertainties of involved astronomical and biological parameters, the Drake Equation
typically predicts that there should be many exoplanets in our galaxy hosting active, communicative
civilizations (ACCs). These optimistic calculations are however not supported by evidence, which is
often referred to as the Fermi Paradox. Here, we elaborate on this long-standing enigma by showing
the importance of planetary tectonic style for biological evolution. We summarize growing evidence
that a prolonged transition from Mesoproterozoic active single lid tectonics (1.6 to 1.0 Ga) to modern
plate tectonics occurred in the Neoproterozoic Era (1.0 to 0.541 Ga), which dramatically accelerated
emergence and evolution of complex species. We further suggest that both continents and oceans
are required for ACCs because early evolution of simple life must happen in water but late evolution
of advanced life capable of creating technology must happen on land. We resolve the Fermi Paradox
(1) by adding two additional terms to the Drake Equation: foc
(the fraction of habitable exoplanets
with significant continents and oceans) and fpt
(the fraction of habitable exoplanets with significant
continents and oceans that have had plate tectonics operating for at least 0.5 Ga); and (2) by
demonstrating that the product of foc
and fpt
is very small (< 0.00003–0.002). We propose that the lack
of evidence for ACCs reflects the scarcity of long-lived plate tectonics and/or continents and oceans on
exoplanets with primitive life.
A Giant Impact Origin for the First Subduction on EarthSérgio Sacani
Hadean zircons provide a potential record of Earth's earliest subduction 4.3 billion years ago. Itremains enigmatic how subduction could be initiated so soon after the presumably Moon‐forming giant impact(MGI). Earlier studies found an increase in Earth's core‐mantle boundary (CMB) temperature due to theaccumulation of the impactor's core, and our recent work shows Earth's lower mantle remains largely solid, withsome of the impactor's mantle potentially surviving as the large low‐shear velocity provinces (LLSVPs). Here,we show that a hot post‐impact CMB drives the initiation of strong mantle plumes that can induce subductioninitiation ∼200 Myr after the MGI. 2D and 3D thermomechanical computations show that a high CMBtemperature is the primary factor triggering early subduction, with enrichment of heat‐producing elements inLLSVPs as another potential factor. The models link the earliest subduction to the MGI with implications forunderstanding the diverse tectonic regimes of rocky planets.
Climate extremes likely to drive land mammal extinction during next supercont...Sérgio Sacani
Mammals have dominated Earth for approximately 55 Myr thanks to their
adaptations and resilience to warming and cooling during the Cenozoic. All
life will eventually perish in a runaway greenhouse once absorbed solar
radiation exceeds the emission of thermal radiation in several billions of
years. However, conditions rendering the Earth naturally inhospitable to
mammals may develop sooner because of long-term processes linked to
plate tectonics (short-term perturbations are not considered here). In
~250 Myr, all continents will converge to form Earth’s next supercontinent,
Pangea Ultima. A natural consequence of the creation and decay of Pangea
Ultima will be extremes in pCO2 due to changes in volcanic rifting and
outgassing. Here we show that increased pCO2, solar energy (F⨀;
approximately +2.5% W m−2 greater than today) and continentality (larger
range in temperatures away from the ocean) lead to increasing warming
hostile to mammalian life. We assess their impact on mammalian
physiological limits (dry bulb, wet bulb and Humidex heat stress indicators)
as well as a planetary habitability index. Given mammals’ continued survival,
predicted background pCO2 levels of 410–816 ppm combined with increased
F⨀ will probably lead to a climate tipping point and their mass extinction.
The results also highlight how global landmass configuration, pCO2 and F⨀
play a critical role in planetary habitability.
Constraints on Neutrino Natal Kicks from Black-Hole Binary VFTS 243Sérgio Sacani
The recently reported observation of VFTS 243 is the first example of a massive black-hole binary
system with negligible binary interaction following black-hole formation. The black-hole mass (≈10M⊙)
and near-circular orbit (e ≈ 0.02) of VFTS 243 suggest that the progenitor star experienced complete
collapse, with energy-momentum being lost predominantly through neutrinos. VFTS 243 enables us to
constrain the natal kick and neutrino-emission asymmetry during black-hole formation. At 68% confidence
level, the natal kick velocity (mass decrement) is ≲10 km=s (≲1.0M⊙), with a full probability distribution
that peaks when ≈0.3M⊙ were ejected, presumably in neutrinos, and the black hole experienced a natal
kick of 4 km=s. The neutrino-emission asymmetry is ≲4%, with best fit values of ∼0–0.2%. Such a small
neutrino natal kick accompanying black-hole formation is in agreement with theoretical predictions.
Detectability of Solar Panels as a TechnosignatureSérgio Sacani
In this work, we assess the potential detectability of solar panels made of silicon on an Earth-like
exoplanet as a potential technosignature. Silicon-based photovoltaic cells have high reflectance in the
UV-VIS and in the near-IR, within the wavelength range of a space-based flagship mission concept
like the Habitable Worlds Observatory (HWO). Assuming that only solar energy is used to provide
the 2022 human energy needs with a land cover of ∼ 2.4%, and projecting the future energy demand
assuming various growth-rate scenarios, we assess the detectability with an 8 m HWO-like telescope.
Assuming the most favorable viewing orientation, and focusing on the strong absorption edge in the
ultraviolet-to-visible (0.34 − 0.52 µm), we find that several 100s of hours of observation time is needed
to reach a SNR of 5 for an Earth-like planet around a Sun-like star at 10pc, even with a solar panel
coverage of ∼ 23% land coverage of a future Earth. We discuss the necessity of concepts like Kardeshev
Type I/II civilizations and Dyson spheres, which would aim to harness vast amounts of energy. Even
with much larger populations than today, the total energy use of human civilization would be orders of
magnitude below the threshold for causing direct thermal heating or reaching the scale of a Kardashev
Type I civilization. Any extraterrrestrial civilization that likewise achieves sustainable population
levels may also find a limit on its need to expand, which suggests that a galaxy-spanning civilization
as imagined in the Fermi paradox may not exist.
The solar dynamo begins near the surfaceSérgio Sacani
The magnetic dynamo cycle of the Sun features a distinct pattern: a propagating
region of sunspot emergence appears around 30° latitude and vanishes near the
equator every 11 years (ref. 1). Moreover, longitudinal flows called torsional oscillations
closely shadow sunspot migration, undoubtedly sharing a common cause2. Contrary
to theories suggesting deep origins of these phenomena, helioseismology pinpoints
low-latitude torsional oscillations to the outer 5–10% of the Sun, the near-surface
shear layer3,4. Within this zone, inwardly increasing differential rotation coupled with
a poloidal magnetic field strongly implicates the magneto-rotational instability5,6,
prominent in accretion-disk theory and observed in laboratory experiments7.
Together, these two facts prompt the general question: whether the solar dynamo is
possibly a near-surface instability. Here we report strong affirmative evidence in stark
contrast to traditional models8 focusing on the deeper tachocline. Simple analytic
estimates show that the near-surface magneto-rotational instability better explains
the spatiotemporal scales of the torsional oscillations and inferred subsurface
magnetic field amplitudes9. State-of-the-art numerical simulations corroborate these
estimates and reproduce hemispherical magnetic current helicity laws10. The dynamo
resulting from a well-understood near-surface phenomenon improves prospects
for accurate predictions of full magnetic cycles and space weather, affecting the
electromagnetic infrastructure of Earth.
Extensive Pollution of Uranus and Neptune’s Atmospheres by Upsweep of Icy Mat...Sérgio Sacani
In the Nice model of solar system formation, Uranus and Neptune undergo an orbital upheaval,
sweeping through a planetesimal disk. The region of the disk from which material is accreted by
the ice giants during this phase of their evolution has not previously been identified. We perform
direct N-body orbital simulations of the four giant planets to determine the amount and origin of solid
accretion during this orbital upheaval. We find that the ice giants undergo an extreme bombardment
event, with collision rates as much as ∼3 per hour assuming km-sized planetesimals, increasing the
total planet mass by up to ∼0.35%. In all cases, the initially outermost ice giant experiences the
largest total enhancement. We determine that for some plausible planetesimal properties, the resulting
atmospheric enrichment could potentially produce sufficient latent heat to alter the planetary cooling
timescale according to existing models. Our findings suggest that substantial accretion during this
phase of planetary evolution may have been sufficient to impact the atmospheric composition and
thermal evolution of the ice giants, motivating future work on the fate of deposited solid material.
Exomoons & Exorings with the Habitable Worlds Observatory I: On the Detection...Sérgio Sacani
The highest priority recommendation of the Astro2020 Decadal Survey for space-based astronomy
was the construction of an observatory capable of characterizing habitable worlds. In this paper series
we explore the detectability of and interference from exomoons and exorings serendipitously observed
with the proposed Habitable Worlds Observatory (HWO) as it seeks to characterize exoplanets, starting
in this manuscript with Earth-Moon analog mutual events. Unlike transits, which only occur in systems
viewed near edge-on, shadow (i.e., solar eclipse) and lunar eclipse mutual events occur in almost every
star-planet-moon system. The cadence of these events can vary widely from ∼yearly to multiple events
per day, as was the case in our younger Earth-Moon system. Leveraging previous space-based (EPOXI)
lightcurves of a Moon transit and performance predictions from the LUVOIR-B concept, we derive
the detectability of Moon analogs with HWO. We determine that Earth-Moon analogs are detectable
with observation of ∼2-20 mutual events for systems within 10 pc, and larger moons should remain
detectable out to 20 pc. We explore the extent to which exomoon mutual events can mimic planet
features and weather. We find that HWO wavelength coverage in the near-IR, specifically in the 1.4 µm
water band where large moons can outshine their host planet, will aid in differentiating exomoon signals
from exoplanet variability. Finally, we predict that exomoons formed through collision processes akin
to our Moon are more likely to be detected in younger systems, where shorter orbital periods and
favorable geometry enhance the probability and frequency of mutual events.
Emergent ribozyme behaviors in oxychlorine brines indicate a unique niche for...Sérgio Sacani
Mars is a particularly attractive candidate among known astronomical objects
to potentially host life. Results from space exploration missions have provided
insights into Martian geochemistry that indicate oxychlorine species, particularly perchlorate, are ubiquitous features of the Martian geochemical landscape. Perchlorate presents potential obstacles for known forms of life due to
its toxicity. However, it can also provide potential benefits, such as producing
brines by deliquescence, like those thought to exist on present-day Mars. Here
we show perchlorate brines support folding and catalysis of functional RNAs,
while inactivating representative protein enzymes. Additionally, we show
perchlorate and other oxychlorine species enable ribozyme functions,
including homeostasis-like regulatory behavior and ribozyme-catalyzed
chlorination of organic molecules. We suggest nucleic acids are uniquely wellsuited to hypersaline Martian environments. Furthermore, Martian near- or
subsurface oxychlorine brines, and brines found in potential lifeforms, could
provide a unique niche for biomolecular evolution.
Continuum emission from within the plunging region of black hole discsSérgio Sacani
The thermal continuum emission observed from accreting black holes across X-ray bands has the potential to be leveraged as a
powerful probe of the mass and spin of the central black hole. The vast majority of existing ‘continuum fitting’ models neglect
emission sourced at and within the innermost stable circular orbit (ISCO) of the black hole. Numerical simulations, however,
find non-zero emission sourced from these regions. In this work, we extend existing techniques by including the emission
sourced from within the plunging region, utilizing new analytical models that reproduce the properties of numerical accretion
simulations. We show that in general the neglected intra-ISCO emission produces a hot-and-small quasi-blackbody component,
but can also produce a weak power-law tail for more extreme parameter regions. A similar hot-and-small blackbody component
has been added in by hand in an ad hoc manner to previous analyses of X-ray binary spectra. We show that the X-ray spectrum
of MAXI J1820+070 in a soft-state outburst is extremely well described by a full Kerr black hole disc, while conventional
models that neglect intra-ISCO emission are unable to reproduce the data. We believe this represents the first robust detection of
intra-ISCO emission in the literature, and allows additional constraints to be placed on the MAXI J1820 + 070 black hole spin
which must be low a• < 0.5 to allow a detectable intra-ISCO region. Emission from within the ISCO is the dominant emission
component in the MAXI J1820 + 070 spectrum between 6 and 10 keV, highlighting the necessity of including this region. Our
continuum fitting model is made publicly available.
WASP-69b’s Escaping Envelope Is Confined to a Tail Extending at Least 7 RpSérgio Sacani
Studying the escaping atmospheres of highly irradiated exoplanets is critical for understanding the physical
mechanisms that shape the demographics of close-in planets. A number of planetary outflows have been observed
as excess H/He absorption during/after transit. Such an outflow has been observed for WASP-69b by multiple
groups that disagree on the geometry and velocity structure of the outflow. Here, we report the detection of this
planet’s outflow using Keck/NIRSPEC for the first time. We observed the outflow 1.28 hr after egress until the
target set, demonstrating the outflow extends at least 5.8 × 105 km or 7.5 Rp This detection is significantly longer
than previous observations, which report an outflow extending ∼2.2 planet radii just 1 yr prior. The outflow is
blueshifted by −23 km s−1 in the planetary rest frame. We estimate a current mass-loss rate of 1 M⊕ Gyr−1
. Our
observations are most consistent with an outflow that is strongly sculpted by ram pressure from the stellar wind.
However, potential variability in the outflow could be due to time-varying interactions with the stellar wind or
differences in instrumental precision.
Encryption in Microsoft 365 - ExpertsLive Netherlands 2024Albert Hoitingh
In this session I delve into the encryption technology used in Microsoft 365 and Microsoft Purview. Including the concepts of Customer Key and Double Key Encryption.
In his public lecture, Christian Timmerer provides insights into the fascinating history of video streaming, starting from its humble beginnings before YouTube to the groundbreaking technologies that now dominate platforms like Netflix and ORF ON. Timmerer also presents provocative contributions of his own that have significantly influenced the industry. He concludes by looking at future challenges and invites the audience to join in a discussion.
Pushing the limits of ePRTC: 100ns holdover for 100 daysAdtran
At WSTS 2024, Alon Stern explored the topic of parametric holdover and explained how recent research findings can be implemented in real-world PNT networks to achieve 100 nanoseconds of accuracy for up to 100 days.
Enchancing adoption of Open Source Libraries. A case study on Albumentations.AIVladimir Iglovikov, Ph.D.
Presented by Vladimir Iglovikov:
- https://www.linkedin.com/in/iglovikov/
- https://x.com/viglovikov
- https://www.instagram.com/ternaus/
This presentation delves into the journey of Albumentations.ai, a highly successful open-source library for data augmentation.
Created out of a necessity for superior performance in Kaggle competitions, Albumentations has grown to become a widely used tool among data scientists and machine learning practitioners.
This case study covers various aspects, including:
People: The contributors and community that have supported Albumentations.
Metrics: The success indicators such as downloads, daily active users, GitHub stars, and financial contributions.
Challenges: The hurdles in monetizing open-source projects and measuring user engagement.
Development Practices: Best practices for creating, maintaining, and scaling open-source libraries, including code hygiene, CI/CD, and fast iteration.
Community Building: Strategies for making adoption easy, iterating quickly, and fostering a vibrant, engaged community.
Marketing: Both online and offline marketing tactics, focusing on real, impactful interactions and collaborations.
Mental Health: Maintaining balance and not feeling pressured by user demands.
Key insights include the importance of automation, making the adoption process seamless, and leveraging offline interactions for marketing. The presentation also emphasizes the need for continuous small improvements and building a friendly, inclusive community that contributes to the project's growth.
Vladimir Iglovikov brings his extensive experience as a Kaggle Grandmaster, ex-Staff ML Engineer at Lyft, sharing valuable lessons and practical advice for anyone looking to enhance the adoption of their open-source projects.
Explore more about Albumentations and join the community at:
GitHub: https://github.com/albumentations-team/albumentations
Website: https://albumentations.ai/
LinkedIn: https://www.linkedin.com/company/100504475
Twitter: https://x.com/albumentations
UiPath Test Automation using UiPath Test Suite series, part 5DianaGray10
Welcome to UiPath Test Automation using UiPath Test Suite series part 5. In this session, we will cover CI/CD with devops.
Topics covered:
CI/CD with in UiPath
End-to-end overview of CI/CD pipeline with Azure devops
Speaker:
Lyndsey Byblow, Test Suite Sales Engineer @ UiPath, Inc.
Full-RAG: A modern architecture for hyper-personalizationZilliz
Mike Del Balso, CEO & Co-Founder at Tecton, presents "Full RAG," a novel approach to AI recommendation systems, aiming to push beyond the limitations of traditional models through a deep integration of contextual insights and real-time data, leveraging the Retrieval-Augmented Generation architecture. This talk will outline Full RAG's potential to significantly enhance personalization, address engineering challenges such as data management and model training, and introduce data enrichment with reranking as a key solution. Attendees will gain crucial insights into the importance of hyperpersonalization in AI, the capabilities of Full RAG for advanced personalization, and strategies for managing complex data integrations for deploying cutting-edge AI solutions.
Sudheer Mechineni, Head of Application Frameworks, Standard Chartered Bank
Discover how Standard Chartered Bank harnessed the power of Neo4j to transform complex data access challenges into a dynamic, scalable graph database solution. This keynote will cover their journey from initial adoption to deploying a fully automated, enterprise-grade causal cluster, highlighting key strategies for modelling organisational changes and ensuring robust disaster recovery. Learn how these innovations have not only enhanced Standard Chartered Bank’s data infrastructure but also positioned them as pioneers in the banking sector’s adoption of graph technology.
Alt. GDG Cloud Southlake #33: Boule & Rebala: Effective AppSec in SDLC using ...James Anderson
Effective Application Security in Software Delivery lifecycle using Deployment Firewall and DBOM
The modern software delivery process (or the CI/CD process) includes many tools, distributed teams, open-source code, and cloud platforms. Constant focus on speed to release software to market, along with the traditional slow and manual security checks has caused gaps in continuous security as an important piece in the software supply chain. Today organizations feel more susceptible to external and internal cyber threats due to the vast attack surface in their applications supply chain and the lack of end-to-end governance and risk management.
The software team must secure its software delivery process to avoid vulnerability and security breaches. This needs to be achieved with existing tool chains and without extensive rework of the delivery processes. This talk will present strategies and techniques for providing visibility into the true risk of the existing vulnerabilities, preventing the introduction of security issues in the software, resolving vulnerabilities in production environments quickly, and capturing the deployment bill of materials (DBOM).
Speakers:
Bob Boule
Robert Boule is a technology enthusiast with PASSION for technology and making things work along with a knack for helping others understand how things work. He comes with around 20 years of solution engineering experience in application security, software continuous delivery, and SaaS platforms. He is known for his dynamic presentations in CI/CD and application security integrated in software delivery lifecycle.
Gopinath Rebala
Gopinath Rebala is the CTO of OpsMx, where he has overall responsibility for the machine learning and data processing architectures for Secure Software Delivery. Gopi also has a strong connection with our customers, leading design and architecture for strategic implementations. Gopi is a frequent speaker and well-known leader in continuous delivery and integrating security into software delivery.
Securing your Kubernetes cluster_ a step-by-step guide to success !KatiaHIMEUR1
Today, after several years of existence, an extremely active community and an ultra-dynamic ecosystem, Kubernetes has established itself as the de facto standard in container orchestration. Thanks to a wide range of managed services, it has never been so easy to set up a ready-to-use Kubernetes cluster.
However, this ease of use means that the subject of security in Kubernetes is often left for later, or even neglected. This exposes companies to significant risks.
In this talk, I'll show you step-by-step how to secure your Kubernetes cluster for greater peace of mind and reliability.
GraphSummit Singapore | The Future of Agility: Supercharging Digital Transfor...Neo4j
Leonard Jayamohan, Partner & Generative AI Lead, Deloitte
This keynote will reveal how Deloitte leverages Neo4j’s graph power for groundbreaking digital twin solutions, achieving a staggering 100x performance boost. Discover the essential role knowledge graphs play in successful generative AI implementations. Plus, get an exclusive look at an innovative Neo4j + Generative AI solution Deloitte is developing in-house.
Goodbye Windows 11: Make Way for Nitrux Linux 3.5.0!SOFTTECHHUB
As the digital landscape continually evolves, operating systems play a critical role in shaping user experiences and productivity. The launch of Nitrux Linux 3.5.0 marks a significant milestone, offering a robust alternative to traditional systems such as Windows 11. This article delves into the essence of Nitrux Linux 3.5.0, exploring its unique features, advantages, and how it stands as a compelling choice for both casual users and tech enthusiasts.
zkStudyClub - Reef: Fast Succinct Non-Interactive Zero-Knowledge Regex ProofsAlex Pruden
This paper presents Reef, a system for generating publicly verifiable succinct non-interactive zero-knowledge proofs that a committed document matches or does not match a regular expression. We describe applications such as proving the strength of passwords, the provenance of email despite redactions, the validity of oblivious DNS queries, and the existence of mutations in DNA. Reef supports the Perl Compatible Regular Expression syntax, including wildcards, alternation, ranges, capture groups, Kleene star, negations, and lookarounds. Reef introduces a new type of automata, Skipping Alternating Finite Automata (SAFA), that skips irrelevant parts of a document when producing proofs without undermining soundness, and instantiates SAFA with a lookup argument. Our experimental evaluation confirms that Reef can generate proofs for documents with 32M characters; the proofs are small and cheap to verify (under a second).
Paper: https://eprint.iacr.org/2023/1886
Threats to mobile devices are more prevalent and increasing in scope and complexity. Users of mobile devices desire to take full advantage of the features
available on those devices, but many of the features provide convenience and capability but sacrifice security. This best practices guide outlines steps the users can take to better protect personal devices and information.
Essentials of Automations: The Art of Triggers and Actions in FMESafe Software
In this second installment of our Essentials of Automations webinar series, we’ll explore the landscape of triggers and actions, guiding you through the nuances of authoring and adapting workspaces for seamless automations. Gain an understanding of the full spectrum of triggers and actions available in FME, empowering you to enhance your workspaces for efficient automation.
We’ll kick things off by showcasing the most commonly used event-based triggers, introducing you to various automation workflows like manual triggers, schedules, directory watchers, and more. Plus, see how these elements play out in real scenarios.
Whether you’re tweaking your current setup or building from the ground up, this session will arm you with the tools and insights needed to transform your FME usage into a powerhouse of productivity. Join us to discover effective strategies that simplify complex processes, enhancing your productivity and transforming your data management practices with FME. Let’s turn complexity into clarity and make your workspaces work wonders!
Removing Uninteresting Bytes in Software FuzzingAftab Hussain
Imagine a world where software fuzzing, the process of mutating bytes in test seeds to uncover hidden and erroneous program behaviors, becomes faster and more effective. A lot depends on the initial seeds, which can significantly dictate the trajectory of a fuzzing campaign, particularly in terms of how long it takes to uncover interesting behaviour in your code. We introduce DIAR, a technique designed to speedup fuzzing campaigns by pinpointing and eliminating those uninteresting bytes in the seeds. Picture this: instead of wasting valuable resources on meaningless mutations in large, bloated seeds, DIAR removes the unnecessary bytes, streamlining the entire process.
In this work, we equipped AFL, a popular fuzzer, with DIAR and examined two critical Linux libraries -- Libxml's xmllint, a tool for parsing xml documents, and Binutil's readelf, an essential debugging and security analysis command-line tool used to display detailed information about ELF (Executable and Linkable Format). Our preliminary results show that AFL+DIAR does not only discover new paths more quickly but also achieves higher coverage overall. This work thus showcases how starting with lean and optimized seeds can lead to faster, more comprehensive fuzzing campaigns -- and DIAR helps you find such seeds.
- These are slides of the talk given at IEEE International Conference on Software Testing Verification and Validation Workshop, ICSTW 2022.
Communications Mining Series - Zero to Hero - Session 1DianaGray10
This session provides introduction to UiPath Communication Mining, importance and platform overview. You will acquire a good understand of the phases in Communication Mining as we go over the platform with you. Topics covered:
• Communication Mining Overview
• Why is it important?
• How can it help today’s business and the benefits
• Phases in Communication Mining
• Demo on Platform overview
• Q/A
Observability Concepts EVERY Developer Should Know -- DeveloperWeek Europe.pdfPaige Cruz
Monitoring and observability aren’t traditionally found in software curriculums and many of us cobble this knowledge together from whatever vendor or ecosystem we were first introduced to and whatever is a part of your current company’s observability stack.
While the dev and ops silo continues to crumble….many organizations still relegate monitoring & observability as the purview of ops, infra and SRE teams. This is a mistake - achieving a highly observable system requires collaboration up and down the stack.
I, a former op, would like to extend an invitation to all application developers to join the observability party will share these foundational concepts to build on:
Observability Concepts EVERY Developer Should Know -- DeveloperWeek Europe.pdf
Alma observations of_the_hh46_47_molecular_outflow
1. submitted to The Astrophysical Journal (March 31, 2013)
Preprint typeset using LATEX style emulateapj v. 5/2/11
ALMA OBSERVATIONS OF THE HH 46/47 MOLECULAR OUTFLOW
H´ector G. Arce
Department of Astronomy,Yale University, P.O. Box 208101, New Haven, CT 06520-8101, USA
Diego Mardones
Departamento de Astronom´ıa, Universidad de Chile, Casilla 36-D, Santiago, Chile
Stuartt A. Corder
Joint ALMA Observatory, Av. Alonso de C´ordova 3107, Vitacura, Santiago, Chile
Guido Garay
Departamento de Astronom´ıa, Universidad de Chile, Casilla 36-D, Santiago, Chile
Alberto Noriega-Crespo
Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125, USA
and
Alejandro C. Raga
Instituto de Ciencias Nucleares, UNAM, Ap. 70-543, 04510 D.F., M´exico
submitted to The Astrophysical Journal (March 31, 2013)
ABSTRACT
The morphology, kinematics and entrainment mechanism of the HH 46/47 molecular outflow were
studied using new ALMA Cycle 0 observations. Results show that the blue and red lobes are strikingly
different. We argue that these differences are partly due to contrasting ambient densities that result
in different wind components having a distinct effect on the entrained gas in each lobe. A 29-point
mosaic, covering the two lobes at an angular resolution of about 3 , detected outflow emission at
much higher velocities than previous observations, resulting in significantly higher estimates of the
outflow momentum and kinetic energy than previous studies of this source, using the CO(1–0) line.
The morphology and the kinematics of the gas in the blue lobe are consistent with models of out-
flow entrainment by a wide-angle wind, and a simple model describes the observed structures in the
position-velocity diagram and the velocity-integrated intensity maps. The red lobe exhibits a more
complex structure, and there is evidence that this lobe is entrained by a wide-angle wind and a colli-
mated episodic wind. Three major clumps along the outflow axis show velocity distribution consistent
with prompt entrainment by different bow shocks formed by periodic mass ejection episodes which
take place every few hundred years. Position-velocity cuts perpendicular to the outflow cavity show
gradients where the velocity increases towards the outflow axis, inconsistent with outflow rotation.
Additionally, we find evidence for the existence of a small outflow driven by a binary companion.
Subject headings: ISM: jets and outflows — stars: formation — ISM: Herbig-Haro objects — ISM:
individual (HH 46, HH 47)
1. INTRODUCTION
As stars form inside molecular clouds, they eject mass
in energetic bipolar outflows. The resulting bipolar wind
from a young stellar object (YSO) may reveal itself
through Herbig-Haro (HH) objects observed in the opti-
cal, H2 emission knots in the infrared (IR), and molecular
(CO) outflows observed at millimeter (mm) wavelengths.
HH objects delineate highly collimated jets and their (in-
ternal or leading) bow shocks. The H2 IR emission also
arises from recently shocked gas and in many cases it
traces the bow-shock wings that extend toward the driv-
ing source. CO outflows map the ambient gas that has
been swept-up well after it has been entrained by the
protostellar wind and has cooled. Hence, these differ-
ent manifestations provide complementary views: while
HH objects and H2 emission provide a “snapshot” of the
current shock interaction, the CO outflow trace the pro-
tostar’s mass loss history (e.g., Richer et al. 2000).
Protostellar winds inject energy and momentum into
the surroundings, thereby perturbing the star-formation
environment. Outflows may be responsible for the clear-
ing of material from the core (Arce & Sargent 2006), a
process that could result in the termination of the infall
phase (e.g., Velusamy & Langer 1998), affect the star
formation efficiency in the cloud (e.g., Matzner & Mc-
Kee 2000; Nakamura & Li 2007; Machida & Hosokawa
2013), and determine the mass of stars (Myers 2008). In
addition, outflows can affect the kinematics, density and
chemistry of a substantial volume of their parent clouds,
and thus can be important to the turbulent dynamics and
energetics of their host cores. How exactly protostellar
arXiv:1304.0674v3[astro-ph.SR]27Jul2013
2. 2 Arce, et al.
winds entrain and disperse the surrounding gas and feed
their parent clouds turbulence remains a mystery. High
angular (and velocity) resolution, multi-wavelength, ob-
servations of outflows are needed to probe all different
outflow manifestations in order to compare them with
hydrodynamic numerical simulations and shock models
to obtain a complete picture of protostellar winds, the
entrainment process and their impact on their surround-
ings.
Here we present Atacama Large Millimeter/sub-
millimeter Array (ALMA) observations of the HH 46/47
molecular outflow. The high resolution data were ob-
tained with the aim of studying the entrainment process,
the underlying protostellar wind and the properties of the
molecular outflow. The observed outflow is driven by HH
47 IRS (a.k.a., HH 46 IRS 1, IRAS 08242-5050), a low-
mass Class I YSO with a total luminosity of about 12 L
in the Bok globule ESO 216-6A, located on the outskirts
of the Gum Nebula at a distance of 450 pc (Schwartz
1977; Reipurth et al. 2000; Noriega-Crespo et al. 2004).
The source lies very close to the edge of the Bok globule,
which explains why the blue (northern) lobe of the HH
46/47 bipolar flow is clearly seen at optical wavelengths
outside the globule, while within ∼ 2 of the source the
red lobe (which mostly lies inside the globule) is best
seen in IR images. Hubble Space Telescope (HST) ob-
servations indicate that HH 47 IRS is actually a binary
system, where the two components of the system are ob-
served to be separated by only 0. 26 or about 120 AU
(Reipurth et al. 2000). Wide-field, narrow-band Hα and
[S II] optical images of the region by Stanke et al. (1999)
reveal two groups of HH objects at distances, from the
position of HH 47 IRS, of about 1.3 pc to the northeast
(in the blue lobe) and southwest (in the red lobe), out-
side the parent globule. These results showed that the
well-known HH 46/47 flow (extending 0.57 pc from HH
47D in the northeast to HH 47C to the southwest) is, in
fact, the innermost part of a giant HH flow that extends
2.6 pc on the plane of the sky.
Many of the properties of the HH 46/47 flow have
been determined through extensive optical and IR ob-
servations. The combination of optical spectral data and
proper motion studies of the HH knots (using ground-
based telescopes) allowed an estimate of the flow’s in-
clination to the plane of the sky (∼ 30◦
) and an aver-
age jet velocity of 300 km s−1
(Reipurth 1989; Reipurth
& Heathcote 1991; Eisl¨oeffel & Mundt 1994; Micono et
al. 1998). More recently, proper motion studies (using
HST) of the blue lobe optical HH knots, in combination
with the results from spectroscopic Fabry-Per´ot observa-
tions (Morse et al. 1994), allowed Hartigan et al. (2005)
to estimate an average orientation angle, with respect
to the plane of the sky, of about 37◦
. Infrared images
show how shocked H2 emission in the southwestern (red-
shifted) lobe traces the walls of a 36 (0.08 pc) wide
cavity that extends ∼ 2 (0.26 pc) to the position of HH
47C (Eisl¨offel et al. 1994; Noriega-Crespo et al. 2004).
The HH 46/47 molecular outflow has only been fully
mapped at low resolution (with beams larger than 24 )
by several authors, using the two lowest rotational transi-
tions of CO (Chernin & Masson 1991; Olberg et al. 1992;
van Kempen et al. 2009). APEX observations of higher
CO transitions (up to 7-6) of a smaller area (80 × 80 )
surrounding the source show the molecular outflow gas
reaches temperatures as high as 100 K (van Kempen et
al. 2009). Moreover, recent Herschel PACS observations
of a region within 30 from the source reveal the exis-
tence of hot CO and H2O (thought to be partly produced
by non-dissociative C-shocks) and OH and [OI] emission
from dissociative J-shocks where the protostellar wind
interacts with the surrounding dense core (van Kempen
et al. 2010; Wampfler et al. 2010).
Even though the extensive multi-wavelength studies of
this source have helped understand the physics of proto-
stellar jets, the lack of high-resolution molecular outflow
observations (until now) has hampered our ability to ob-
tain a complete picture of the outflow phenomenon in
HH 46/47, the entrainment process and the protostellar
wind’s impact on the cloud. Here we present the first in-
terferometric, high-resolution (beam ∼ 3 ) observations
of the HH 46/47 molecular (CO) outflow and compare
the morphology and kinematics to existing (simple) mod-
els of outflow entrainment. In a future paper we will use
hydrodynamical simulations to model the outflow and
aim to provide more stringent constraints on the launch-
ing and entrainment mechanisms in this flow.
2. OBSERVATIONS
The observations were carried out using ALMA from
28 December 2011 to 25 January 2012, during the Early
Science Cycle 0 phase. The Band 3 data were obtained
over eleven scheduling blocks, with 16 to 18 antennas in
the (Cycle 0) compact configuration, consisting of pro-
jected baselines in the range of 12 to 277 m. The corre-
lator was configured to observe three windows with the
highest spectral resolution (δν = 30.5 kHz), with a band-
width of 58.6 MHz and centered at 115.27 GHz, the fre-
quency of the CO (1-0) transition, and at 100.88 and
100.07 GHz. We only detected line emission in the 115.27
GHz window, which has a velocity resolution of 0.08 km
s−1
. No line was detected in the other two windows, and
were therefore used to map the continuum emission. We
mapped our sources using a rectangular 29-point mosaic,
with contiguous pointings separated by 24.5 , oriented at
a position angle (P.A.) of about 58◦
, designed to cover
the length of the HH 46/47 outflow from HH 47A, in the
northeast, to HH 46C, in the southwest, and the width of
the red outflow lobe seen in IR images (see, e.g., Noriega-
Crespo et al. 2004). The mosaic had three rows, the two
outer rows consisted of 10 pointings and the central row
had 9, resulting in a map of about 1.2 × 4.2 , centered
on 08h
25m
41s
.5, −51◦
00 47 (J2000).
The nearby quasar J0845-5458 was used for phase and
gain calibration. Flux calibration was carried out us-
ing observations of Mars, and J0538-440 and 3c279 were
used as bandpass calibrators. The visibility data were
edited, calibrated and imaged (using the CLEAN algo-
rithm) in CASA, using 0.5 cells and 1024 cells in each
spacial dimension. For the spectral data we defined a dif-
ferent clean region for each channel, encircling the area
with the brightest emission. The resulting synthesized
beam for the 12
CO(1–0) data cube is 3.2 × 2.4 , with
a PA= 16.5◦
, and the (1σ) rms is 25 mJy beam−1
in a
(spectroscopically smoothed) map with a velocity reso-
lution of 0.5 km s−1
. The continuum was obtained by
averaging the emission over all channels in the two win-
dows close to 100 GHz with no detected line emission,
3. ALMA Observations of HH 46/47 3
B0
AA
cloud
edge
R1
R2
R3
beam
Fig. 1.— Integrated intensity map of the HH 46/47 CO(1–0) outflow. Blue (red) contours represent the blueshifted (redshifted) lobe. The
blue lobe is integrated over −6.8 < vout < −1.3 km s−1. The lowest contour and subsequent contour steps are 0.2 and 0.25 Jy beam−1 km
s−1, respectively. The red lobe is integrated over 1.3 < vout < 6.7 km s−1. The lowest contour and subsequent contour steps are 0.25 and
0.3 Jy beam−1 km s−1, respectively. Green contours show the 3 mm continuum emission surrounding HH 47 IRS. The lowest contour and
subsequent contour steps are 1.3 and 1 mJy beam−1, respectively. The thick grey line delineates the edge of the globule as traced by our
CO data close to the cloud velocity (see Figure 3). The synthesized beam of the CO map is shown on the lower left corner of the figure.
Grey diagonal parallel dashed lines show the edges of our map. The position of redshifted outflow clumps R1, R2 and R3 is shown, as well
as that of the blueshifted clump B0 and clump A. The dark dashed line passing through B0, HH 47 IRS and A indicates the position of
the p − v cut shown in Figure 11.
resulting in a bandwidth of 117.2 MHz. The synthesized
beam and rms for the continuum map are 3.1 × 2.2
(PA= 15◦
), and 0.33 mJy beam−1
3. RESULTS
3.1. Continuum Source
We detected continuum thermal dust emission at 100
GHz near the position of the protostar, with a peak in-
tensity of 8.1 mJy beam−1
. A Gaussian fit puts the con-
tinuum peak at 8h
25m
43.s
8,-51◦
00 36 (J2000.0), which
we adopt as the position of HH 47 IRS, and it is con-
sistent with that given by Reipurth et al. (2000). The
continuum emission is barely resolved, and it is slightly
extended toward the southwest (see Figure 1). The total
flux density is 14 mJy, and we follow Schnee et al. (2010)
and Dunham et al. (2012) to estimate the mass of the
envelope using the dust continuum emission, assuming a
dust temperature (Td) of 30 K and gas-to-dust ratio of
100. We estimate the dust opacity (κ) at 3 mm to be
0.9 cm2
g−1
, by extrapolating the value of κ at 1.3 mm
obtained by Ossenkopf & Henning (1994) for dust with a
thin ice mantle after 105
yr of coagulation at a gas den-
sity of 106
cm−3
, and assuming an emissivity spectral
index (β) of 1. Using the above assumptions, we obtain
a total (gas and dust) mass associated with the contin-
uum emission of 0.4 M . This estimate depends mostly
on the assumed dust temperature, opacity and emissivity
index. Single dish observations of the dust continuum of
HH 47 by (van Kempen et al. 2009) and observations of
other Class 0 and Class I sources (e.g., Arce & Sargent
2006) indicate that Td in the range of 20 to 40 K is a rea-
sonable assumption. The dust opacity at 3 mm can vary
depending on the adopted dust model and the assumed
β (which may range from about 0.3 to 1.5 for Class 0 and
Class I sources, e.g., Arce & Sargent 2006). Reasonable
variations of these quantities lead to possible variations
in the mass estimate by a factor of two to three.
The angular resolution of our continuum is not enough
to resolve different peaks associated with the two differ-
ent binary components of the system. The observed con-
tinuum emission most probably traces the envelope that
surrounds the binary system, and observations with an
order of magnitude higher angular resolution are needed
to investigate whether each component has its own sep-
arate circumstellar envelope.
3.2. Line Data and the Molecular Outflow
Integrated intensity maps of the CO(1–0) blueshifted
and redshifted emission from the HH 46/47 molecular
outflow are displayed in Figure 1. The most striking as-
pect of this outflow is the clear difference in size and mor-
phology between the two different lobes; the red (south-
western) lobe extends approximately 2 from the source,
while the blue (northeastern) lobe only extends up to
about 30 from the powering YSO. This asymmetry had
4. 4 Arce, et al.
been noted in earlier, lower angular resolution, observa-
tions of the CO outflow and it is generally assumed that
it is due to the fact that the HH 47 IRS is close to the
edge of the parent globule (i.e, Chernin & Masson 1991;
Olberg et al. 1992; van Kempen et al. 2009). The proto-
stellar wind’s blueshifted (northeastern) lobe breaks-out
of the cloud, where there is little molecular gas for it to
entrain, while the redshifted lobe dives into the globule
and is able to entrain much more gas along its path.
In addition to the drastic difference in length, each
lobe exhibits dissimilar morphologies most likely caused
by differing dominant entrainment processes. The blue
lobe shows mainly a parabolic morphology, with a P.A.
of about 60◦
. The morphology and the velocity structure
of the blue lobe suggests this molecular outflow is mostly
being formed by the entrainment of cloud material by a
wide angle protostellar wind (see Section 4.1). We also
detect in the blue lobe a small protuberance southeast
of the continuum source (labeled B0 in Figure 1), which
we argue is due to the outflow from a binary companion
(see Section 4.4). The red lobe, on the other hand, has a
V-shape near the source, with an opening angle of about
65◦
. Starting at about 30 from the source, the inte-
grated intensity contours mostly trace the southern and
northern outflow cavity walls, which extend up to 80
and 2 , respectively, from the source. We suspect that
these structures trace the limb-brightened walls of an
approximately cylindrical shell produced by the outflow-
cloud interaction. In addition, we detect three distinct
clumps of gas along the outflow axis which we label R1,
R2 and R3 (see Figure 1). In Section 4.2, we argue that
these result from approximately periodic mass ejections
driven by the central protostar.
In Figure 2 we plot the spectrum at the position of
brightest integrated intensity in the CO(1–0) outflow
map of Olberg et al. (1992). We compare the spectrum
shown in Figure 4 of Olberg et al. (1992) with a spectrum
obtained from our CO map, smoothed to the same reso-
lution as the beam size of the Olberg et al. observations
(44 ). From this comparison we see that the ALMA ob-
servations recover most (if not all) of the emission at LSR
velocities greater than 6.5 km s−1
and less than 3.5 km
s−1
, and it is clear that we do not fully recover the emis-
sion at velocities close to that of the cloud (vLSR ∼ 5 km
s−1
, van Kempen et al. 2009). We are therefore confident
that our ALMA data can be used to reliably study the
emission at outflow velocities greater than about 1.5 km
s−1
.
3.2.1. Channel Maps
Figure 3 shows the emission over the outflow veloc-
ity range between approximately −6 and 6 km s−1
, and
reveals how the CO emission structure of the region de-
pends on velocity. We define outflow velocity (vout) as
the LSR velocity of the emission minus the cloud LSR
velocity. Panels in the upper row (blueshifted velocities)
and lower row (redshifted velocities) present the emission
averaged over a 1 km s−1
range centered on the velocity
indicated in the upper right corner of each panel. Panels
in the center row show emission averaged over 0.5 km
s−1
wide range for velocities close to that of the cloud.
We note that low intensity outflow emission is detected
at higher outflow velocities than those shown in Figure 3.
VLSR [km s-1]
AntennaTemperature[K]
Fig. 2.— Comparison between CO(1–0) spectrum from Olberg
et al. (1992) and our ALMA observations. The spectrum shown in
green is the same one shown in Figure 4 of Olberg et al. (1992),
which comes from the brightest position in the redshifted lobe of
their the map. The black histogram shows the spectrum at the
same position from a map using our ALMA data that have been
smoothed to the same beam size as that of the Olberg et al. data
(44 ). The spectrum from the ALMA data is also smoothed to a
velocity resolution of 0.5 km s−1 for easier visual comparison with
the Olberg et al. spectrum.
This weak high-velocity emission is only seen when inte-
grating the emission over a larger velocity range ( 5 km
s−1
), see Section 4.1 and Section 4.2.
In Figure 3 the first two panels in the upper row
(vout = −5.8 and −4.8 km s−1
) show an approximately
symmetric parabolic (low-intensity) structure extending
northeast of the source. At lower blue outflow velocities
the emission is stronger and the northern wall of the lobe
extends further from the source than the southern wall.
At vout = −2.8 km s−1
we detect two faint arcs of emis-
sion, about 40 northeast and 2 southwest of the proto-
star, which we ascribe to the limb-brightened edge of the
host globule. These arcs are brighter closer to the cloud
velocity (see panels at vout = −0.1 and 0.4 km s−1
). At
vout = −1.8 km s−1
the blueshifted outflow emission is
very bright and it is concentrated in an inclined V-shape
structure northeast of the source. It is only at very low
outflow velocities that we detect the clump B0, about
20 southeast of HH 47 IRS, which very likely traces
the molecular outflow driven by the binary component
that is not driving the main HH 46/47 outflow (see Sec-
tion 4.4). In this panel we also detect faint emission
southwest of the outflow source, coincident with some of
the regions where we detect redshifted outflow emission.
It is possible that the walls of the southwest (mainly red-
shifted) outflow lobe are expanding into the surrounding
cloud (similar to the RNO 91 outflow; Lee & Ho 2005),
and the filamentary blueshifted emission comes from the
front walls of the cavity. In addition, at vout = −1.8 km
s−1
we detect a small relatively bright clump close to the
position of the HH 47C shock (and the redshifted clump
R3) at about 2 southwest from the source, which most
likely arises from gas entrained by HH 47C.
As shown in Figure 2, close to the cloud velocity our
interferometer observations do not fully recover the emis-
sion from the cloud, as the observations are not sensitive
to large scale ( 20 ) structures. This is the reason why
the channel maps from vout = −1.1 to 0.9 km s−1
appear
so clumpy and the emission at these velocities cannot be
used to obtain reliable estimates of the outflow or cloud
5. ALMA Observations of HH 46/47 5
Blue
Red
Cloud
cloud edge cloud edge
cloud edge
A AA
cloud edge
Fig. 3.— Channel maps of the CO(1–0) emission. Top (bottom) row shows blueshifted (redshifted) emission, where each panel shows
the emission average over 1 km s−1. The lowest contour and subsequent contour steps are 0.075 and 0.15 Jy beam−1, respectively. The
middle row shows velocities near the cloud velocity, and each panel shows the emission average over 0.5 km s−1. The lowest contour and
subsequent contour steps are 0.15 and 0.3 Jy beam−1, respectively. The central outflow velocity is given in the upper right corner of each
panel in units of km s−1. The synthesized beam is shown on the lower right corner of each panel. The red cross shows the position of HH
47 IRS.
TABLE 1
Outflows Properties
Lobe Massa [10−2 M ] Momentuma, b [10−2 M km s−1] Energya, b [1042 erg]
Tex = 15 K 50 K 100 K 15 K 50 K 100 K 15 K 50 K 100 K
Blue 1 2 3 3 / 6 8 / 16 15 / 30 3 / 12 8 / 32 14 / 56
Red 3 8 14 12 / 24 27 / 54 51 / 102 9 / 36 21 / 84 39 / 156
a Estimates are obtained assuming emission is optically thin. Values should be treated as lower limits.
b Values before the slash are not corrected for the outflow inclination and those after the slash are corrected assuming
an inclination of the outflow axis, with respect to the plane of the sky, of 30◦
.
mass nor to map the overall distribution of the cloud
molecular gas. There are, however, a few small-scale fea-
tures that are discernible among the clumpy mess. Even
at vout = −1.1 km s−1
we are able to identify the V-like
structure just north-east of HH 47 IRS due to the blue
outflow lobe, and a clump of gas close to the position
of HH 47C. At the velocity of the cloud (i.e., the vout
= −0.1 and 0.4 km s−1
panels) we detect emission from
the edge of the cloud, which is coincident with the diffuse
8 µm emission observed in Spitzer Space Telescope im-
ages of the region that borders the edge of the host glob-
ule (Noriega-Crespo et al. 2004; Velusamy et al. 2007).
This structure seems to trace the outer parts of the cloud
that are being heated by the UV radiation from the stars
that produce the Gum Nebula. Acceleration of the gas
at the globule’s edge caused by a UV-radiation-induced
photoablation flow could explain the fact that we detect
the globule’s edge at two different velocities separated by
∼ 3 km s−1
(i.e., at vout ∼ 0 and vout ∼ −3 km s−1
). Cer-
tainly, a more detailed study of the cloud’s kinematics is
needed to understand the origin of the velocity structure
at the globule’s edge.
The vout = 0.4 km s−1
panel also exhibits a bright
structure that extends northeast of the source and co-
incides with the HH 46 optical nebula (see Section 4.1).
This vey low velocity emission could be due to the gas
that is entrained by the expanding back wall of the north-
east (mainly blueshifted) lobe. At vout = 0.9 km s−1
the
6. 6 Arce, et al.
overall structure of the CO emission is similar to the
integrated intensity image of the redshifted lobe in Fig-
ure 1, yet there are some notable differences. These in-
clude a bright narrow structure that extends northeast of
the source (coincident with the blue lobe), and the fact
that the wide angle morphology of the southwest lobe
is more prominent here than in the integrated intensity
map (which we argue in Section 4.2 is evidence for the
existence of a wide-angle wind).
Similar to the blue lobe, the redshifted outflow lobe
is brighter at lower outflow velocities. The vout= 1.7
km s−1
panel shows the strongest emission, where the
highest intensity is seen close to the source and on the
southern and northern walls of the outflow lobe. In this
panel the CO emission shows a wide-angle morphology
close to the source, and the emission associated with the
northern outflow wall is somewhat extended (as opposed
to a simple narrow structure as seen at higher outflow
velocities). The three redshifted clumps (R1, R2 and
R3) are seen most clearly at vout = 2.7 and 3.7 km s−1
,
but they are also detected out to vout ∼ 5 km s−1
. The
channel maps also show that from vout = 1.7 km s−1
to
vout = 5.7 km s−1
the redshifted lobe becomes slightly
narrower as the velocity increases.
3.2.2. Outflow Mass, Momentum and Energy
To obtain a reliable estimate of the outflow mass we
would need to know the opacity of the 12
CO(1–0) line,
as in outflows the opacity is expected to vary with veloc-
ity (Bally et al. 1999; Yu et al. 1999; Arce & Goodman
2001b). One way to estimate the opacity of the 12
CO(1–
0) line is using the ratio of 12
CO(1–0) to 13
CO(1–0).
Unfortunately, there are no existing observations of the
13
CO(1–0) emission with an angular resolution (and sen-
sitivity) similar to our 12
CO ALMA map that would al-
low us to properly correct for the opacity. We thus es-
timate the mass assuming the line is optically thin, and
warn that our masses are very likely underestimated, by
a factor of few or even as much as an order of magnitude
(e.g., Cabrit & Bertout 1990; Arce & Goodman 2001b;
Offner et al. 2011). We follow Bourke et al. (1997) to
estimate the outflow properties from the CO(1–0) data,
assuming an abundance ratio of [12
CO]/[H2] = 10−4
, as
in Olberg et al. (1992).
An estimate of the CO outflow excitation temperature
is needed to calculate the outflow mass. However, there
is a very wide range of temperature values given in the
literature for the HH 46/47 molecular outflow. Chernin
& Masson (1991) use the ratio of brightness tempera-
ture between the CO(3 − 2) and CO(2 − 1) at outflow
velocities to estimate an outflow excitation temperature
(Tex) of 8.5 ± 1 K (but use a value of 10 K in their out-
flow mass calculations). On the other hand, Olberg et
al. (1992) estimate an excitation temperature, at outflow
velocities, of 15 K using the intensity ratio of CO(1–0) to
CO(2–1). van Kempen et al. (2009) use their multi-line
observations to conduct a thorough and detailed study
of the physical conditions of the gas surrounding HH 47
IRS, and estimate larger values for the outflow excita-
tion temperature (between 50 and 150 K, but most likely
about 100 K). Without ALMA observations of higher CO
transition lines we cannot make our own detailed map of
Tex, with an angular resolution comparable to our CO
data, along the entire extent of the outflow. Therefore,
we calculate the outflow mass, and other outflow prop-
erties shown in Table 1, using different values of exci-
tation temperature. It is clear that uncertainties in Tex
result in highly inaccurate estimates of the outflow prop-
erties. We note that if we consider the same excitation
temperature and the same velocity ranges used by Ol-
berg et al. (1992) for the two different outflow lobes (i.e.,
Tex = 15 K, vout = −5.0 to −1.5 km s−1
for the blue
lobe and vout = 1.5 to 7.5 km s−1
for the red lobe), we
obtain a total outflow mass of 3.6 × 10−2
M , similar
to the value of 0.03 M obtained by Olberg et al. This
is consistent with Figure 2, which shows that our inter-
ferometric observations recover most (if not all) of the
emission at outflow velocities greater than 1.5 km s−1
.
Our observations are much more sensitive than any
previous study of the HH 46/47 molecular outflow, which
allows us to detect outflow emission over a much wider
velocity range. In this work we measure the outflow mass
(Mout), momentum [Pout = Σ Mout(vout) vout], and en-
ergy [Eout = 0.5 Σ Mout(vout) v2
out] over the velocity
range where we detect outflow emission with intensity
greater than 3σ, that is −30 < vout < −1.6 km s−1
for
the blue lobe and 1.4 < vout < 40 km s−1
for the red lobe
(see Table 1). In both lobes the very high velocity outflow
(|vout| > 20 km s−1
) is constrained to within about 15 of
the source. Detection of low-intensity CO(1–0) outflow
emission at very high velocities resulted in our estimates
of the outflow kinetic energy and momentum to be signif-
icantly higher than those of Olberg et al. (1992). This im-
plies that other similar molecular outflows may be much
more energetic than what previous (low-sensitivity) ob-
servations indicated and outflows may have the potential
to have more impact on their surrounding cloud than pre-
viously thought.
We can compare the properties of the jet with those of
the molecular outflow in order to investigate whether the
jet injects enough momentum into the cloud and drive
the molecular outflow. Assuming Tex = 50 K, the mo-
mentum of the red lobe is ∼ 0.5 M km s−1
(see Ta-
ble 1). The mass loss rate of the HH 47 jet (inward of
HH 47A) was estimated by Hartigan et al. (1994) to be
about 4 × 10−7
M yr−1
. Using a jet velocity of 300 km
s−1
(see above), the momentum rate in the jet is then
estimated to be 1.2 × 10−4
M km s−1
yr−1
. We adopt
the age of the wind to be 9000 yr, the dynamic age of the
parsec-scale HH flow associated with HH 46/47, discov-
ered by Stanke et al. (1999). Assuming the red lobe has
a similar momentum rate as the blue lobe and that the
rate has been approximately constant over the lifetime
of the flow, we estimate that the jet has been able to in-
ject a total of about 1 M km s−1
into the surrounding
medium, which could be enough to drive the molecular
outflow (if the assumptions above are correct). However,
it should be kept in mind that our estimate of the molec-
ular outflow momentum is probably underestimated by
a factor of a few to possibly an order of magnitude (since
we assumed the emission is optically thin). Moreover,
if we instead use the dynamic age of the jet within the
globule (using the size of the jet comparable to the molec-
ular outflow red lobe), that is ∼ 1000 yr, the estimated
momentum injected by the jet into the cloud would be
approximately 0.1 M km s−1
. It thus seem that there
7. ALMA Observations of HH 46/47 7
is material ejected by the protostar which is not detected
in the optical or IR –and therefore not included in the
estimate of the jet mass loss rate quoted above– that
contributes to the momentum injected by the protostel-
lar wind into the cloud that drives the molecular outflow.
4. DISCUSSION
4.1. Blue lobe: evidence for wide-angle wind
As mentioned above, we detect blueshifted outflow
emission out to larger velocities than what is presented
in Figure 3. The intensity of the high-velocity emission is
very low and it is necessary to sum over velocity ranges
wider than 1 km s−1
in order to detect significant emis-
sion. In Figure 4 we show four velocity maps, integrated
over different velocity ranges, that show the morphol-
ogy of the high-velocity blue lobe gas. From this figure,
it is clear that at higher outflow velocities the emission
extends farther from the source, compared to lower ve-
locities. In addition, in panels b through d the emis-
sion shows an elongated ring or shell-like structure. This
general behavior, in both morphology and velocity dis-
tribution, is consistent with the expected properties of a
molecular outflow entrained by a wide-angle wind (Shu
et al. 1991; Lee et al. 2000; Arce & Goodman 2002).
In order to further investigate the underlying proto-
stellar wide-angle wind and entrainment mechanism in
the blue lobe, we constructed a position-velocity (p − v)
diagram along the axis of the outflow, shown in Figure 5.
This figure shows an inclined parabolic structure, as ex-
pected for an outflow entrained by a wide-angle wind
with a non-zero inclination of the outflow axis with re-
spect to the plane of the sky (Lee et al. 2000, 2001). The
relatively high angular resolution and sensitivity of our
ALMA data results in one of the most (if not the most)
clear case where such a parabolic structure is detected in
the p − v diagram of a molecular outflow lobe.
We follow the simple analytical model by Lee et al.
(2000) to describe the blue lobe of the HH 46/47 molec-
ular outflow. In this model, which is based on the study
by Li & Shu (1996), the molecular outflow is made up
of the gas that is swept-up by a wide-angle wind that
propagates into a flattened (toroid-like) dense core. The
resulting molecular outflow can then be modeled by a ra-
dially expanding parabolic shell with a velocity structure
in which velocity increases with distance (i.e., a Hubble
law velocity structure). A diagram of the model is shown
in Figure 21 of Lee et al. (2000), and in cylindrical coor-
dinates (with the z-axis along the symmetry axis of the
wind and the R-axis perpendicular to it) the morphology
of the shell can be represented by the equation z = CR2
,
while the velocity components of the shell along the z
and R axes are represented by vz = voz, vR = voR. In
these equations C and vo are free parameters with units
of arcsec−1
and km s−1
arcsec−1
, which are constrained
by the shape of the molecular outflow shell and the shape
of the p − v diagram, respectively.
A map of the high-velocity blue lobe parabolic struc-
ture was produced by integrating the emission for outflow
velocities between −26 and −4 km s−1
, in order to avoid
“contaminating” emission from the cloud and the binary
component outflow (see Figure 3). We rotated the map
by −30◦
and fit a parabola (z = CR2
) to the structure.
The fit gives a value for C of 0.3 ± 0.05, where the errors
indicate the range of values that provide a reasonable fit
to the map. We then fit the p−v diagram with the wide-
angle wind model of Lee et al. (2000) described above.
We constrain the inclination angle with respect to the
plane of the sky (i) to 30 ± 10◦
, close to the values de-
rived by Eisl¨oeffel & Mundt (1994) and Hartigan et al.
(2005), assuming a distance to the parent globule of 450
pc. We find that a value of vo = 2.3±0.2 km s−1
arcsec−1
and an value of i = 29◦
± 1◦
result in a reasonable fit to
the p − v cut. The errors indicate the range of values for
which reasonable fits are attained, and choosing signif-
icantly different values for these two parameters would
result in a parabolic curve with a different width or in-
clination compared to the p − v diagram obtained from
our data.
The wide-angle wind model can also be used to predict
the shape of the molecular outflow shell at different ve-
locities (Lee et al. 2000; Hirano et al. 2010). We used the
parameters derived above, and plot the predicted shape
at different outflow velocities in Figure 4. For each panel
the dash ellipse shows the expected shape of the molecu-
lar outflow shell, according to the wide-angle wind model,
at the outflow velocity at the center of the velocity in-
terval of integration (shown at the top of each panel).
The model provides a reasonable match to the velocity
range-integrated intensity maps, as the observed emis-
sion structure follows the general trend expected from
the model. That is, at lower outflow velocities the out-
flow shell is more compact and its southwestern end co-
incides with the position of the source, while at higher
velocities the shell is more extended and lies further away
from the source.
This simple analytical model is probably not the only
model that may reproduce the observed morphology. For
example, in a jet (or collimated wind) with varying ejec-
tion velocity, such as HH 46/47 (e.g., Raga et al. 1990),
fast-moving ejecta can collide with previously ejected
(slower-moving) material. As a result of such collisions
the wind material may expand and push ambient mate-
rial in a direction perpendicular to the jet axis, possibly
creating a wide cavity with low-collimation (e.g., Suttner
et al. 1997; Cabrit et al. 1997). However, the fact that we
can reasonably fit the velocity range-integrated intensity
maps (Figure 4) and the p−v diagram (Figure 5) with the
wide-angle wind model described above suggests that the
observed blue lobe could very likely have been formed by
the entrainment of a wide-angle wind and the ambient
cloud. Our data, however, cannot distinguish between
possible wind-launching mechanisms that can produce
wide-angle winds (e.g., X-wind, Shang et al. 2006 or disk
winds, Pudritz et al. 2006). We would need higher an-
gular resolution data to probe down to less than ∼ 50
AU from the source in order to possibly discriminate be-
tween different launching mechanisms (e.g., Ferreira et
al. 2006).
It might seem conflicting that the blue outflow lobe ap-
pears to be entrained by a wide-angle wind, when it is co-
incident with the base of a well-studied jet (see Figure 6).
However, it is possible for both a collimated wind compo-
nent (i.e., a jet) to co-exist with a wide-angle wind (see,
e.g., models by Shang et al. 2007; Pudritz et al. 2007;
Fendt 2009; Tomida et al. 2013). In fact, this is not the
first source to exhibit such characteristics. Three exam-
8. 8 Arce, et al.
-24.3 < vout < -19.3 km/s -19.3 < vout < -14.3 km/s -14.3 < vout < -9.3 km/s -9.3 < vout < -6.8 km/s
Fig. 4.— Velocity range-integrated intensity maps of the CO blueshifted emission. The velocity interval of integration is given on the top
of each panel. In all panels the lowest contour and contour steps are 0.07 Jy beam−1 km s−1. The dash blue ellipse in each panel shows
the expected shape of the molecular outflow shell driven by a wide-angle wind using the model described in the text (see Section 4.1).
The model shell is calculated using the outflow velocity at the center of the velocity interval of integration, and the same parameters used
to model the p − v diagram in Figure 5. The synthesized beam is shown on the lower left corner of each panel. The red cross shows the
position of HH 47 IRS.
ples where a “dual-component” wind have been invoked
to explain the mm and optical/IR outflow observations
are HH 111 (Nagar et al. 1997, Lee et al. 2000, however
see Lefloch et al. 2007 for an alternative explanation),
HH 315 (Arce & Goodman 2002), and B5-IRS 1 (Yu et
al. 1999). In the first two cases the protostellar source is
close to the cloud edge, the blue optical jet (or HH flow) is
clearly seen to reside outside the dense parts of the cloud,
and the morphology of the molecular outflow’s blue lobe
is consistent with it being formed by a wide-angle wind
(similar to HH 46/47). This is possible if the underlying
protostellar wind has both a collimated (jet) and a wide-
angle component and the gas in the blue lobe is mostly
entrained by the wide-angle component. The reason that
the wide-angle wind dominates the gas entrainment in
these sources (including HH 46/47) is possibly due to
the fact that the jets lie in a region of very low density
molecular gas, on the outskirts of the cloud. Numerical
simulations of jet shock-driven outflows show that most
of the gas entrainment takes place at (or near) the head of
the bow-shock (e.g., Smith et al. 1997; Lee et al. 2001),
while in a radially expanding wide-angle wind entrain-
ment mostly takes place in a wide-angle shell originating
at the source. Hence, in a dual component wind where
the jet bow shocks mostly reside outside the cloud, the
Outflow Velocity [km s-1]
Offsetfromsource[arcsec]
Fig. 5.— Position-velocity diagram along the axis of the blue
lobe. The figure was constructed using a map with velocity resolu-
tion of 0.5 km s−1, and summing the emission over a 7.5 (about 3
beams) wide cut, with a position angle of 60◦. Contours have value
of 0.35, 0.66, 1, 1.5, 2, 3 Jy beam−1, and subsequent steps of 1 un-
til 10 Jy beam−1, and thereon in steps of 2 Jy beam−1. The light
blue parabola shows the model fit to the data (see Section 4.1).
circumstellar molecular gas will mostly be accelerated
by the wide-angle wind component close to the source,
where there is enough molecular material for the wind to
entrain and form the observed molecular outflow.
Further evidence that the blue lobe of the HH 46/47
molecular outflow is entrained by a dual-component
wind is observed by comparing the morphology of the
blueshifted gas and that of the optical jet. In Figure 6 we
show contours of the low-velocity blueshifted lobe plotted
over the HST image of the HH 47/46 jet. The northern
wall of the CO blue lobe follows the northern edge of the
optical nebula, which implies that the bright parabolic
structure observed in CO traces the walls of the outflow
cavity. The jet’s wiggling structure suggests that the jet
axis changes with time or precesses (i.e, Reipurth et al.
2000). In Figure 6 we show the opening angle of the pre-
cession cone in the plane of the sky, delimited by lines
Fig. 6.— Comparison of blue CO lobe and optical image of HH
46/47 jet. The HST image was taken with the [SII] (F673N) fil-
ter in 2008 by Hartigan et al. (2011). Contours show the emission
integrated over the velocity range from -6.8 to -3.2 km s−1. This
velocity range was chosen to avoid contamination from cloud emis-
sion and B0. The lowest contour and subsequent contour steps are
0.15 and 0.2 Jy beam−1 km s−1, respectively. The yellow cross
shows the position of HH 47 IRS. The two black dash lines connect
the position of the source to outermost positions of the wiggling
jet, with respect to the outflow axis. The dotted pink line perpen-
dicular to the outflow cavity shows the position of the p − v cut
shown in Figure 10a.
9. ALMA Observations of HH 46/47 9
Declination(J2000)
Right Ascension (J2000) Right Ascension (J2000) Right Ascension (J2000)
1.2 < vout < 2.7 km/s 2.7 < vout < 6.2 km/s 6.2 < vout < 21.2 km/s
Wide-angle
outflow
bifurcation in
cavity wall
bifurcation in
cavity wall
R1
R2
R3
Fig. 7.— Velocity range-integrated intensity maps of the CO redshfited emission. The velocity interval of integration is given at the
top of each panel. In the left, middle and right panels the lowest contour and contour steps are 0.2, 0.105, and 0.2 Jy beam−1 km s−1,
respectively. The synthesized beam is shown on the lower left corner of each panel. The red cross shows the position of HH 47 IRS.
that connect HH 47 IRS and the bright emission knots at
the most extreme angles with respect to the protostellar
source. It is clear that the opening angle of the molec-
ular outflow lobe is substantially wider than that of the
jet precession cone. It is therefore highly unlikely that
precession of the jet alone could, by itself, produce the
wide-angle cavity traced by the CO outflow.
4.2. Red lobe
Compared to the blue lobe, the red lobe of the HH
46/47 molecular outflow exhibits a more complex spatial
and kinematical structure. In Figure 7 we show maps of
the redshifted outflow emission integrated over different
velocity ranges chosen to highlight the different impor-
tant structures discernible at different velocities. These
are discussed in detail below.
4.2.1. Morphological evidence for the existence of a
wide-angle wind
Figure 7a presents a map of the low outflow velocity
emission (1.2 < vout < 2.7 km s−1
), where the lobe shows
a clear wide-angle structure, with an opening angle of
65◦
, within 40 of the source. This wide-angle structure
is drastically different from the morphology of the bright
Wide-angle
reflection nebula
Fig. 8.— Comparison of red CO lobe with Spitzer IRAC 2 (4.5
µm) image. The Spitzer data are from Noriega-Crespo et al. (2004)
and have been reprocessed with a deconvolution algorithm to reach
an angular resolution of ∼ 0.6 − 0.8 , with 60 iterations (see
Noriega-Crespo & Raga 2012 for details). White contours show
the integrated intensity of the CO redshifted lobe (the same as
shown in Figure 1). Black contours show the 3 mm continuum
emission around HH 47 IRS. The lowest contour and subsequent
contour steps are 2 mJy beam−1. The white dash line shows the
position of the p − v cut shown in Figure 10b.
IR outflow cavity walls seen in the IRAC Spitzer observa-
tions (Noriega-Crespo et al. 2004), which is similar to the
structure of the CO outflow red lobe at distances from
the source further than 40 (see Figure 8). The loop-like
structure seen in the IRAC images has been adequately
modeled as the cavity walls of a jet-driven outflow by
Raga et al. (2004). This model, however, does not repro-
duce the wide-angle structure seen in low-velocity CO
emission nor the wide-angle IR nebula seen close to the
source in re-processed IRAC images of HH 46/47 (see
below). It seems, therefore, that the wide-angle struc-
ture is not produced by the collimated (jet) component
responsible for the bright outflow cavity walls seen both
in CO and IR, extending form about 30 to 2 away from
the source. Similar to the blue lobe, the red lobe shows
evidence of both a collimated and a wide-angle wind com-
ponent.
Recently, Velusamy et al. (2007) presented reprocessed
images of the IRAC observations of HH 46/47, which in-
cluded suppression of side lobes from bright sources and
enhanced resolution (compared to the images presented
by Noriega-Crespo et al. 2004). The 3.6 and 4.5 µm
images show diffuse and extended emission close to the
source with a parabolic morphology, with an opening an-
gle of about 110◦
, which Velusamy et al. (2007) argue is
due to scattered light arising from a wide-angle outflow
cavity (see Figure 8). This structure is wider than the
CO outflow lobe, and we suspect we are not able to trace
the full extent of the IR reflection nebula due to the high
opacity of the CO(1–0) at velocities close the ambient
cloud. In the few cases where a molecular outflow has
been mapped in 13
CO, it typically shows a wider opening
angle (at lower outflow velocities) than the lobe traced
by the 12
CO emission and the optical/IR reflection neb-
ula (i.e, Ohashi et al. 1997; Tafalla & Myers 1997; Arce &
Sargent 2006). We expect that future observations using
lines with a lower opacity (or that probe higher densi-
ties) will be able to trace the wide angle cavity outlined
by the faint extended IR emission.
4.2.2. Evidence for episodic mass ejections
Among the most distinct structures in the velocity-
integrated map shown in Figure 7b are three bright and
compact features along the outflow axis. These local-
maxima of emission are the same clumps identified in
Figure 1 as R1, R2, and R3. They are more clearly seen
in Figure 7b because of the limited velocity range used to
produce this figure compared to Figure 1. Table 2 shows
10. 10 Arce, et al.
the distance from the source as well as other physical
properties of each of the molecular clumps. The distance
from the source to R1 (about 0.1 pc) is approximately
equal to the distance between R1 and R2, and the dis-
tance between R2 and R3. This suggests they might be
the result of periodic ejection episodes, similar to those
found in other molecular outflows (e.g., L1448, Bachiller
et al. 1990; RNO 43, Bence et al. 1996; HH 300, Arce
& Goodman 2001b). In fact, R1 and R2 are at similar
distances from HH 47 IRS as the bright bow shock struc-
tures HH 47B and HH 47A, respectively, along the optical
jet, in the opposite (blue) lobe of HH 46/47. These two
HH knots are thought to arise from different mass ejec-
tion episodes (Reipurth & Heathcote 1991), and the R1
and R2 may be associated with the counter-ejections (in
the redshifted lobe) of the mass-loss events that caused
HH 47B and HH 47A. Similarly, R3 is coincident with
HH 47C (in the red lobe), which is thought to be asso-
ciated with the ejection responsible for the HH 47D bow
shock (in the blue lobe).
To further investigate the nature of the outflow clumps
we show, in Figure 9, a p − v diagram along the axis
of the redshifted molecular outflow lobe. At distances
greater than 30 from the source, the p − v diagram
shows three regions where there is a clear increase in the
outflow velocity coincident with the position of the red
outflow clumps. These features in the p−v diagram, gen-
erally referred to as “Hubble wedges” (Arce & Goodman
2001a), show maximum outflow velocity increasing as a
function of distance from the source, within a localized
length along the outflow axis. The general consensus is
that such features are formed by a collimated (jet-like)
episodic flow with a significantly varying mass-ejection
rate, where each clump associated with a Hubble wedge
is produced by the bow-shock entrainment of an individ-
ual mass-ejection event (Arce & Goodman 2001a; Lee et
al. 2001). That is, each clump is mostly made of am-
bient gas that has been swept up and accelerated by a
protostellar wind ejection episode.
In Table 2 we list estimates of the timescale (i.e., age)
for each mass ejection episode in HH 46/47 assuming that
all clumps are moving away from the source at a constant
space velocity. We expect the ejected material will decel-
erate as it moves through the cloud and interacts with the
surrounding medium, which will result in slower veloci-
ties for older ejected material (e.g., Cabrit & Raga 2000;
Goodman & Arce 2004). Yet, we can use an average flow
velocity of the jet (¯vjet) for all outflow clumps to obtain
an estimate of the ejection age for each mass ejection
episode. Existing studies indicate that ¯vjet ∼ 300 km
s−1
for HH 46/47 (Eisl¨oeffel & Mundt 1994; Micono et
al. 1998; Hartigan et al. 2005). Using this velocity, we
estimate that a major mass ejection event in HH 46/47
takes place approximately every 300 yr, consistent with
the results from studies of the optical (blueshifted) jet.
The CO outflow clumps we detect are most likely
made of gas that has been entrained near the current
position of the clump. Observations indicate that the
outflow mass rate in HH 46/47 is of the order of 10−7
M yr−1
(Hartigan et al. 1994; Antoniucci et al. 2008;
Garcia Lopez et al. 2010). From the length of R2 along
the outflow axis (i.e., ∼ 20 ), and assuming a constant
vjet = 300 km s−1
, we estimate that the episodes of
TABLE 2
Properties of clumps in redshifted CO outflow
lobe
Distance from sourcea Agea Massb
Clump (arcsec) (pc) (yrs) (10−3 M )
R1 42 0.1 360 2.1
R2 81 0.2 650 1.8
R3 118 0.3 945 0.7
a Values of linear distance and age have been corrected for
the inclination of the outflow axis, assuming i = 30◦
.
b Mass estimate obtained assuming optically thin emission
and an excitation temperature of 50 K. Values shown should
be treated as lower limits.
high mass ejection last about 102
yrs. With the mass
outflow rate given above this would result in a total of
∼ 10−5
M ejected in the wind, which is about two or-
ders of magnitude less than the estimated gas mass of
R2. The mass loss rate during the episode associated
with R2 would have to be about two orders of magni-
tude higher than the rates estimated for HH 46/47 for
the protostellar wind mass to be similar to the estimated
gas mass of R2. Hence, it seems more likely that the vast
majority of the detected molecular gas in the redshifted
outflow clumps is cloud material that has been entrained
by the protostellar wind rather than material from the
protostellar wind itself.
Episodes of enhanced mass outflow rate are thought
to be caused by an increase in the mass accretion rate
onto the protostar. In the case of HH 46/47, there seems
to be a mechanism that is able to produce an enhance-
ment in the accretion rate every few hundred years. This
timescale is significantly shorter than the estimated or-
bital period of the binaries in the HH 47 IRS system
(see Reipurth et al. 2000). This rules out triggering of
gravitational instabilities in the circumstellar disk of the
source that drives the HH 46/47 outflow by the close
passage of the known binary companion as a mechanism
for enhanced disk accretion. A closer (yet unobserved)
companion would have to exist for companion-disk inter-
actions (Reipurth 2000) to be a feasible mechanism for
triggering episodic mass ejections. Other mechanisms
that could produce episodic accretion (and hence mass
ejection) events have been discussed in the literature,
where disk instabilities are the main cause of enhanced
accretion events (e.g., Vorobyov & Basu 2005; Zhu et al.
2010; Machida et al. 2011). In many of the models the
timescales between successive episode may be very dif-
ferent depending on the assumed input parameters, and
in some of these models successive events of high mass
accretion rate can occur on timescales as low as a few 100
yrs to about 103
yr, consistent with the observed proper-
ties of the HH 46/47 outflow. Future studies of outflow
episodicity using a large sample may help constrain vari-
able accretion models.
Another morphological feature detected in the red-
shifted molecular outflow lobe that may be caused by
multiple mass ejections is the bifurcation of the northern
cavity wall. This feature is seen at low and medium out-
flow velocities (Figures 7a and 7b) at about 1 away from
the protostar along the northern wall of the outflow lobe.
Here the wall appears to divide into two filaments: a
bright component that extends southwest approximately
11. ALMA Observations of HH 46/47 11
R1 R2 R3
Offset from source [arcsec]
OutflowVelocity[kms-1]
Fig. 9.— Position-velocity diagram along the axis of the red lobe.
The figure was constructed using a map with velocity resolution
of 0.08 km s−1, with a position angle of 60◦, and summing the
emission over a 7.5 -wide cut. The lowest contour and subsequent
contour steps are 1 and 1.5 Jy beam−1, respectively. The positions
of the redshifted outflow clumps along the outflow axis are shown.
parallel to the outflow axis (PA ∼ −120◦
) and a fainter
component that makes a sharp southward turn toward
the position of R2 (see Figure 7a and b). Models and sim-
ulations of molecular outflows formed by episodic winds
show that a thin shell or a cavity is formed around each
internal bow shock formed by different ejection episodes
(Gueth et al. 1996; Lee et al. 2001). We thus surmise
that the filamentary feature that connects R2 and the
northern wall of the red lobe traces the shell formed by
the interaction of the ejection episode associated with R2
and the ambient gas. Faint emission connecting R1 to
the southern wall of the lobe may indicate that a similar
structure is also driven by R1.
4.2.3. High-velocity redshifted emission
Figure 7c shows a velocity-integrated map over high
CO outflow velocities in the red lobe (6.2 < vout <
21.2 km s−1
). Here the outflow opening angle near the
source (∼ 50◦
) and the lobe width are smaller than at low
outflow velocities. The overall arc-like morphology of the
northern wall is consistent with the shape expected for
an outflow lobe formed by (jet) bow-shock entrainment
(e.g., Raga & Cabrit 1993; Lee et al. 2001). This and the
other morphological and kinematical features discussed
above imply that the dominant entrainment mechanism
of the CO outflow observed beyond 40 arises from a col-
limated episodic wind with a series of bow shocks along
the axis. On the other hand, near the source, and at low
outflow velocities the molecular outflow appears to have
been formed by the entrainment from a wide-angle wind.
A possible explanation is that the wide-angle component
has a lower velocity (and possibly a lower density) than
the collimated (jet-like and episodic) component. Near
the source, where the ambient density is high, both the
wide-angle and collimated component will entrain the
gas, but the effects of the wide-angle wind will be seen
most clearly at low outflow velocities and at relatively
large angles away from the outflow axis. The faster mov-
ing (and denser) collimated component is able to travel
further away from the source (and even puncture out of
cloud near the position of R3), and thus the CO outflow
further out from the source (and at high-velocities) will
exhibit properties of it being mostly entrained by a col-
limated wind. Certainly, a successful model for the HH
46/47 molecular outflow would need to reproduce the dif-
ference in morphology between the low and high outflow
velocities and at different distances from the source.
4.3. Velocity Gradients in Outflow Cavity
The high sensitivity, high velocity resolution data al-
lowed us to study the kinematics of the outflow cavity in
detail. In Figure 10 we plot the p − v diagrams made by
cuts perpendicular to the outflow cavities of the blue and
red lobes. The figure shows that for both cavities there
is a wide range of velocities present at the position of the
cavity walls, and a gradual velocity gradient with most
emission near the outflow axis at higher velocities than
(most of) the emission closer to the outflow walls. In
the blue lobe, at the position of the outflow cavity walls,
there is detectable CO at velocities from vout ∼ −5 km
s−1
to vout ∼ −0.5 km s−1
. Yet, most of the emission at
these position is at velocities close to that of the ambi-
ent cloud (i.e., between vout of about −2 and −0.5 km
s−1
, see Figure 10a). This in contrast to positions closer
to the outflow axis, where the bulk of the emission is at
slightly higher velocities, between vout of −2 and −3 km
s−1
. A similar velocity distribution, but with much faster
velocities, has been observed in the HH 46/47 optical jet
with fast radial velocities (∼ −100 to −150 km s−1
) in
the jet core and slower velocities (∼ −25 to −50 km s−1
)
at the edges (Morse et al. 1994). In the CO outflow red
lobe we see a spread in velocities (i.e., emission over a
range of vout of about 2 km s−1
) at the position of the
cavity walls (and in the emission inside the outflow cav-
ity), as well as an increase in the average (and minimum)
velocity of the CO as the distance to the center of the
cavity decreases: from an average velocity close to that
of the ambient cloud (vout∼ 0.5 km s−1
) at the outer
cavity wall, to an average vout∼ 2 km s−1
at center of
the outflow lobe (see Figure 10b).
The wide spread in velocities at the position of the cav-
ity walls may be explained by both geometric effects and
the expected interaction between the outflow and the
surrounding cloud. Observations with limited angular
resolution are expected to detect a large range in radial
velocities (i.e., the component of the gas velocity along
the line-of-sight) at the limb-brightened edge of an ex-
panding parabolic (or cylindrical) cavity, as outflow gas
from the front and back side of the cavity wall should
Offset from outflow axis [arcsec]
OutflowVelocity[kms-1]
center
of cavity
southern
cavity
wall
northern
cavity
wall
Offset from outflow axis [arcsec]
center
of cavity
southern outer
cavity wall northern
cavity
wall
inner cavity
wall
emission
inside cavity
Blue lobe
Red lobe
(a)
(b)
Fig. 10.— Position-velocity diagrams perpendicular to the out-
flow axis for the blue (left panel) and red (right panel) lobes. In
both p − v diagrams the offsets are given with respect to the posi-
tion of the outflow axis in the cut. The location of the p−v cuts for
the blue and red lobes are shown in Figures 6 and 8, respectively.
In the left panel the lowest contour and the subsequent contour
steps are 0.2 and 0.15 Jy beam−1, respectively. In the right panel
the lowest contour and the subsequent contour steps are 0.07 and
0.16 Jy beam−1, respectively.
12. 12 Arce, et al.
contribute to the total detected emission. In addition,
given that the cavity wall is where the outflow-cloud in-
teraction takes place, one would expect the gas to be
more turbulent here than close to the cavity center, and
hence show a wider spread in velocities.
It is not clear what causes the observed velocity gra-
dient perpendicular to the outflow axis. The decrease in
velocity of about 1 to 2 km s−1
from the center of the cav-
ity to the cavity walls may be due to different processes.
One possibility is that this behavior in the CO outflow
results from the entrainment of a protostellar wind that
has higher velocities towards the wind axis. For example,
a disk wind where the velocity of the wind depends on
the radius at which is launched (Pudritz et al. 2006) or a
jet made of many small bow-shocks where the entrained
material at the head of the bow shocks (along the center
of the jet) is expected to have higher velocities than the
material entrained at the side wings of the bow shock
(Heathcote et al. 1996). Another alternative is that the
velocity gradient results from the momentum-conserving
wind entrainment that produces the molecular outflow,
where lower CO outflow velocities are expected in denser
regions near the cavity walls (e.g., Arce & Sargent 2004).
An additional possibility is that this is an effect due to
the geometry of an expanding parabolic, conical or cylin-
drical cavity inclined with respect to the plane of the sky.
Undoubtedly, the detected gradient is not due to outflow
rotation, as it has been recently claimed for a few other
sources (e.g., Lee et al. 2009; Zapata et al. 2010; Choi
et al. 2011; Pech et al. 2012). The observed decrease in
velocity from the outflow axis towards the cavity walls is
in contrast with the expected observational signatures of
outflow rotation: a gradient across the entire lobe length
with one side of the lobe showing bluer (or redder) ve-
locities with respect to the other side of the lobe (e.g.,
Launhardt et al. 2009).
4.4. Outflow from binary
As described in Section 3.2.1, the channel maps show
a protuberance extending about 20 southeast of the
source, at low blueshifted outflow velocities (vout ∼
−1.8 km s−1
). We believe that this clump (which we
name B0) is not related to the main blueshifted outflow
lobe, as it does not follow the general parabolic shape
seen at most blue shifted velocities. A p−v diagram ori-
ented along a line from HH 47 IRS to B0, at PA ∼ 132◦
(Figure 11), shows that the maximum velocity increases
from near the source to the position of B0, similar to the
Hubble-wedges of the red outflow clumps. We speculate
that B0 traces a region where an underlying protostellar
wind is entraining molecular gas.
A recent study of the HH 46/47 jet shows that the
proper motion on the plane of the sky of one of the most
recent ejections (within ∼ 3 of HH 47 IRS) is along a
line with a position angle of about 40◦
on the plane of
the sky, while further away (∼ 35 ) from the source the
jet motion has a PA closer to 55◦
(Hartigan et al. 2011).
Thus, it is very unlikely that the ejection responsible for
B0 is part of the flow responsible for the HH 46/47 jet,
and the most likely candidate for powering the outflow
that drives B0 is the other binary companion in the HH
47 IRS binary system not responsible for the main HH
46/47 outflow. Weaker and smaller outflows from binary
components have been observed in other sources (e.g.,
Offset from source [arcsec]
OutflowVelocity[kms-1]
B0
A
Fig. 11.— Position-velocity diagram along the axis of the pro-
posed outflow powered by the binary companion in the HH 47 IRS
system not responsible for the main HH 46/47 outflow. The lo-
cation of the p − v cut is shown in Figure 1. The lowest contour
and the subsequent contour steps are 0.1 and 0.3 Jy beam−1, re-
spectively. The locations of the blueshifted outflow clump B0 and
clump A, along the p − v cut, are shown.
HH 111, Cernicharo & Reipurth 1996; BHR 71, Parise et
al. 2006; L1448C Hirano et al. 2010; IRAM 04191+1522,
Lee et al. 2005, Chen et al. 2012), and we believe that
HH 46/47 shows another case of drastically different out-
flows arising from binaries in the same system. Current
observations of this system do not have the required an-
gular resolution to resolve which outflow is powered by
each of the binary components in HH 47 IRS.
Figure 11 shows that there is a clump (which we name
A) with very low red (and blue) outflow velocities at
about 30 northwest of HH 47 IRS on what would be
the counter lobe of the outflow associated with B0. The
distance from the source to A is slightly more than the
distance to B0, and the position of A is coincident with
the edge of the globule seen in our CO channel maps
(Figure 3). It is not clear if clump A arises from the
counter ejection of B0 or if it is just cloud emission. Fur-
ther observations are needed to ascertain the nature of
this clump.
5. SUMMARY & CONCLUSIONS
We present the first interferometric map of the molec-
ular (CO) outflow associated with the well-known HH
46/47 flow, powered by HH 47 IRS. With our high veloc-
ity (0.08 km s−1
) and angular (∼ 3 ) resolution ALMA
Cycle 0 observations we have investigated the kinematics
and morphology of the molecular outflow. The 4.2 long
mosaic map of the CO(1–0) emission covers the length
of the HH 46/47 outflow from HH 47A, in the northeast,
to HH 47C, in the southwest, and provides the data to
study both the blueshifted and redshifted molecular out-
flow lobes in detail. Our main conclusions are as follows.
The unprecedented sensitivity of our data enable us to
detect outflow emission at much higher velocities than
previous CO(1–0) studies of the source; up to outflow ve-
locities of about −30 and 40 km s−1
in the blue and red
lobes, respectively. Even though the very high velocity
(|vout| > 20 km s−1
) emission is constrained to about 15
(or 7000 AU) from the source, detection of this outflow
emission results in significantly higher values of the out-
flow kinetic energy and momentum, compared to results
from existing single dish CO(1–0) observations. If HH
46/47 is representative of molecular outflows from low-
13. ALMA Observations of HH 46/47 13
mass stars, our results imply that other similar molecu-
lar outflows may be much more energetic and carry more
momentum than previously thought. The HH 46/47 flow
is the first molecular outflow from a low-mass star to be
mapped in the ALMA Cycle 0 phase and subsequent
ALMA observations using more antennas will provide
even more sensitive maps. From our results we expect
that future outflow studies with ALMA will show that
outflows can have much more impact on their surround-
ing cloud than previously thought.
The blue and red molecular outflow lobes show very
distinct morphologies and kinematics. The blueshifted
lobe only extends up to about 30 (14000 AU) north-
east from HH 47 IRS. The compact size of the molecular
outflow lobe is due to the fact that the outflow-powering
protostar resides at the edge of its parent globule and the
protostellar wind is only able to push and accelerate a
limited amount of molecular material before it leaves the
cloud. The blueshifted lobe shows a very clear parabolic
structure in both the integrated intensity map and in the
position-velocity diagram along the outflow axis. The
morphology and velocity distribution are consistent with
a model where the molecular outflow is formed by the en-
trainment of an underlying wide-angle protostellar wind.
We argue that the co-existence of a wide-angle molecular
outflow and an optical jet in the blue lobe of HH 46/47
is possible if the underlying protostellar wind has both
a collimated (jet) and a wide-angle component. In the
blue lobe, the wide-angle wind component dominates the
gas entrainment because the jet bow shocks lie in a re-
gion with very low ambient density while the wide-angle
component interacts with the environment very close to
the source, where there is enough ambient (molecular)
gas for the wide-angle wind to entrain and form the ob-
served molecular outflow.
The redshifted lobe is about 2 (∼ 0.3 pc) in length, ex-
tending out to the southwest edge of the globule. Within
approximately 40 (18000 AU) of the source the red lobe
shows a wide-angle structure which is very different from
the loop-like structure seen in IR images and the CO lobe
structure at greater distances from the source. Our re-
sults also show that, beyond 40 and along the axis of the
red lobe, the HH 46/47 outflow has three clumps clearly
detected in the integrated intensity map and position-
velocity diagram. Their spatial distribution and velocity
structure indicate that these clumps arise from prompt
entrainment, most probably produced by bow shocks,
arising from quasi-periodic episodes of increased mass
ejection in HH 47 IRS. We argue that, similar to the
blue lobe, the underlying protostellar wind has both a
collimated and a wide-angle component and that close
to the protostar the molecular outflow red lobe is dom-
inantly driven by the wide-angle component while the
CO outflow observed beyond 40 mainly arises from the
entrainment by a collimated episodic wind. The wide-
angle wind of this, or any other, outflow may affect the
infall and the protostar’s mass-assembling process, and
future ALMA observations with higher angular resolu-
tion and using higher density tracers should concentrate
on studying the impact of the wide-angle wind on the
infalling core and circumstellar envelope.
The position of the three molecular outflow clumps
along the axis of the redshifted lobe suggests that they
are caused by the same ejection event that produced
three major bow shocks in the blue lobe observed in the
optical. Our results confirm previous studies that indi-
cate that HH 47 IRS goes through episodes of increased
mass outflow (and accretion) rates every few hundred
years. Future (higher resolution) multi-epoch observa-
tions with ALMA may be able to detect the proper mo-
tion of the bow shock-driven outflow clumps in HH 46/47
and other molecular outflows. These studies could help
in our understanding of outflow variability and constrain
variable accretion models.
Our high velocity resolution data allowed us to study
the kinematics of the outflow cavity and search for sig-
natures of outflow rotation. We find, in both blue and
red lobes, there is outflow emission over a wide range
of velocities at the cavity walls, and the existence of a
gradual gradient where the velocity increases towards the
outflow axis. It is not clear what produces this velocity
structure. Yet, we are certain it is not consistent with
outflow rotation. Future comparison of our data with
numerical models will allow us to investigate the origins
of this kinematic behavior in the entrained gas.
Our CO(1–0) data detect a small clump at blueshifted
velocities southeast of HH 47 IRS, which we believe arises
from the interaction of a protostellar wind driven by the
binary component in HH 47 IRS that does not drive the
main HH 46/47 outflow. The clump, which lies at a
position angle very different from that of the main HH
46/47 flow, has a velocity distribution consistent with it
being formed by bow shock prompt entrainment. Future
observations with an order of magnitude higher angular
resolution than the maps presented here will be able to
confirm our results and resolve which outflow is powered
by each of the binary components in HH 47 IRS.
HGA acknowledges support from his NSF CAREER
award AST-0845619. DM and GG gratefully acknowl-
edges support from CONICYT project BASAL PFB-06.
We thank Chin-Fei Lee for his help with the wide-angle
model. This paper makes use of the following ALMA
data: ADS/JAO.ALMA#2011.0.00367.S. ALMA is a
partnership of ESO (representing its member states),
NSF (USA) and NINS (Japan), together with NRC
(Canada) and NSC and ASIAA (Taiwan), in coopera-
tion with the Republic of Chile. The Joint ALMA Ob-
servatory is operated by ESO, AUI/NRAO and NAOJ.
The National Radio Astronomy Observatory is a facil-
ity of the National Science Foundation operated under
cooperative agreement by Associated Universities, Inc.
Facility: ALMA.
REFERENCES
Antoniucci, S., Nisini, B., Giannini, T., & Lorenzetti, D. 2008,
A&A, 479, 503
Arce, H. G., & Goodman, A. A. 2001a, ApJ, 551, L171
Arce, H. G., & Goodman, A. A. 2001b, ApJ, 554, 132
Arce, H. G., & Goodman, A. A. 2002, ApJ, 575, 928
Arce, H. G., & Sargent, A. I. 2004, ApJ, 612, 342
Arce, H. G., & Sargent, A. I. 2006, ApJ, 646, 1070
14. 14 Arce, et al.
Bachiller, R., Martin-Pintado, J., Tafalla, M., Cernicharo, J., &
Lazareff, B. 1990, A&A, 231, 174
Bally, J., Reipurth, B., Lada, C. J., & Billawala, Y. 1999, AJ,
117, 410
Bence, S. J., Richer, J. S., & Padman, R. 1996, MNRAS, 279, 866
Bourke, T. L., Garay, G., Lehtinen, K. K., et al. 1997, ApJ, 476,
781
Cabrit, S., & Bertout, C. 1990, ApJ, 348, 530
Cabrit, S., & Raga, A. 2000, A&A, 354, 667
Cabrit, S., Raga, A., & Gueth, F. 1997, Herbig-Haro Flows and
the Birth of Stars, 182, 163
Chen, X., Arce, H. G., Dunham, M. M., & Zhang, Q. 2012, ApJ,
747, L43
Cernicharo, J., & Reipurth, B. 1996, ApJ, 460, L57
Chernin, L. M., & Masson, C. R. 1991, ApJ, 382, L93
Choi, M., Kang, M., & Tatematsu, K. 2011, ApJ, 728, L34
Dunham, M. M., Arce, H. G., Bourke, T. L., et al. 2012, ApJ,
755, 157
Eisl¨offel, J., Davis, C. J., Ray, T. P., & Mundt, R. 1994, ApJ,
422, L91
Eisl¨oeffel, J., & Mundt, R. 1994, A&A, 284, 530
Fendt, C. 2009, ApJ, 692, 346
Ferreira, J., Dougados, C., & Cabrit, S. 2006, A&A, 453, 785
Garcia Lopez, R., Nisini, B., Eisl¨offel, J., et al. 2010, A&A, 511,
A5
Goodman, A. A., & Arce, H. G. 2004, ApJ, 608, 831
Gueth, F., Guilloteau, S., & Bachiller, R. 1996, A&A, 307, 891
Hartigan, P., Frank, A., Foster, J. M., et al. 2011, ApJ, 736, 29
Hartigan, P., Heathcote, S., Morse, J. A., Reipurth, B., & Bally,
J. 2005, AJ, 130, 2197
Hartigan, P., Morse, J. A., & Raymond, J. 1994, ApJ, 436, 125
Heathcote, S., Morse, J. A., Hartigan, P., et al. 1996, AJ, 112,
1141
Hirano, N., Ho, P. P. T., Liu, S.-Y., et al. 2010, ApJ, 717, 58
Launhardt, R., Pavlyuchenkov, Y., Gueth, F., et al. 2009, A&A,
494, 147
Lee, C.-F., Hirano, N., Palau, A., et al. 2009, ApJ, 699, 1584
Lee, C.-F., & Ho, P. T. P. 2005, ApJ, 624, 841
Lee, C.-F., Ho, P. T. P., & White, S. M. 2005, ApJ, 619, 948
Lee, C.-F., Mundy, L. G., Reipurth, B., Ostriker, E. C., & Stone,
J. M. 2000, ApJ, 542, 925
Lee, C.-F., Stone, J. M., Ostriker, E. C., & Mundy, L. G. 2001,
ApJ, 557, 429
Lefloch, B., Cernicharo, J., Reipurth, B., Pardo, J. R., & Neri, R.
2007, ApJ, 658, 498
Li, Z.-Y., & Shu, F. H. 1996, ApJ, 472, 211
Machida, M. N., & Hosokawa, T. 2013, arXiv:1302.4176
Machida, M. N., Inutsuka, S.-i., & Matsumoto, T. 2011, ApJ,
729, 42
Matzner, C. D., & McKee, C. F. 2000, ApJ, 545, 364
Micono, M., Davis, C. J., Ray, T. P., Eisloeffel, J., & Shetrone,
M. D. 1998, ApJ, 494, L227
Morse, J. A., Hartigan, P., Heathcote, S., Raymond, J. C., &
Cecil, G. 1994, ApJ, 425, 738
Myers, P. C. 2008, ApJ, 687, 340
Nagar, N. M., Vogel, S. N., Stone, J. M., & Ostriker, E. C. 1997,
ApJ, 482, L195
Nakamura, F., & Li, Z.-Y. 2007, ApJ, 662, 395
Noriega-Crespo, A., Moro-Mart´ın, A., Carey, S., et al. 2004,
ApJS, 154, 402
Noriega-Crespo, A & Raga, A.C. 2012, ApJ, 750, 101
Offner, S. S. R., Lee, E. J., Goodman, A. A., & Arce, H. 2011,
ApJ, 743, 91
Ohashi, N., Hayashi, M., Ho, P. T. P., & Momose, M. 1997, ApJ,
475, 211
Olberg, M., Reipurth, B., & Booth, R. S. 1992, A&A, 259, 252
Ossenkopf, V., & Henning, T. 1994, A&A, 291, 943
Parise, B., Belloche, A., Leurini, S., et al. 2006, A&A, 454, L79
Pech, G., Zapata, L. A., Loinard, L., & Rodr´ıguez, L. F. 2012,
ApJ, 751, 78
Pudritz, R. E., Rogers, C. S., & Ouyed, R. 2006, MNRAS, 365,
1131
Pudritz, R. E., Ouyed, R., Fendt, C., & Brandenburg, A. 2007,
Protostars and Planets V, 277
Raga, A. C., Binette, L., Canto, J., & Calvet, N. 1990, ApJ, 364,
601
Raga, A., & Cabrit, S. 1993, A&A, 278, 267
Raga, A. C., Noriega-Crespo, A., Gonz´alez, R. F., & Vel´azquez,
P. F. 2004, ApJS, 154, 346
Reipurth, B. 1989, European Southern Observatory Conference
and Workshop Proceedings, 33, 247
Reipurth, B. 2000, AJ, 120, 3177
Reipurth, B., & Heathcote, S. 1991, A&A, 246, 511
Reipurth, B., Yu, K. C., Heathcote, S., Bally, J., & Rodr´ıguez,
L. F. 2000, AJ, 120, 1449
Richer, J. S., Shepherd, D. S., Cabrit, S., Bachiller, R., &
Churchwell, E. 2000, Protostars and Planets IV, 867
Shang, H., Allen, A., Li, Z.-Y., et al. 2006, ApJ, 649, 845
Shang, H., Li, Z.-Y., & Hirano, N. 2007, Protostars and Planets
V, ed. B. Reipurth, D. Jewitt, & K. Keil (Tucson, AZ: Univ.
Arizona Press), 261
Schnee, S., Enoch, M., Johnstone, D., et al. 2010, ApJ, 718, 306
Schwartz, R. D. 1977, ApJ, 212, L25
Smith, M. D., Suttner, G., & Yorke, H. W. 1997, A&A, 323, 223
Shu, F. H., Ruden, S. P., Lada, C. J., & Lizano, S. 1991, ApJ,
370, L31
Stanke, T., McCaughrean, M. J., & Zinnecker, H. 1999, A&A,
350, L43
Suttner, G., Smith, M. D., Yorke, H. W., & Zinnecker, H. 1997,
A&A, 318, 595
Tomida, K., Tomisaka, K., Matsumoto, T., et al. 2013, ApJ, 763,
6
Tafalla, M., & Myers, P. C. 1997, ApJ, 491, 653
van Kempen, T. A., van Dishoeck, E. F., G¨usten, R., et al. 2009,
A&A, 501, 633
van Kempen, T. A., Kristensen, L. E., Herczeg, G. J., et al. 2010,
A&A, 518, L121
Velusamy, T., & Langer, W. D. 1998, Nature, 392, 685
Velusamy, T., Langer, W. D., & Marsh, K. A. 2007, ApJ, 668,
L159
Vorobyov, E. I., & Basu, S. 2005, ApJ, 633, L137
Wampfler, S. F., Herczeg, G. J., Bruderer, S., et al. 2010, A&A,
521, L36
Yu, K. C., Billawala, Y., & Bally, J. 1999, AJ, 118, 2940
Zapata, L. A., Schmid-Burgk, J., Muders, D., et al. 2010, A&A,
510, A2
Zhu, Z., Hartmann, L., Gammie, C. F., et al. 2010, ApJ, 713, 1134