The harps serach_for_southern_exoplanets_02Sérgio Sacani
The document presents an analysis of additional radial velocity measurements of the M dwarf stars Gl 433 and Gl 667C, obtained with the HARPS spectrograph. It finds:
- For Gl 433, one planet (Gl 433b) with a minimum mass of about 5.5 Earth masses and an orbital period of about 7 days. Longer period radial velocity variations are also detected, likely due to magnetic activity cycles.
- For Gl 667C, two planets are found. Gl 667Cb has a minimum mass of about 5.5 Earth masses and an orbital period of about 7 days. Gl 667Cc has a minimum mass of about 4.25 Earth masses and orbits in the habitable zone of its star with a
The document summarizes the first results from an ambitious HARPS program to detect Earth-like planets around nearby solar-type stars using high-precision radial velocity measurements. It reports the discovery of five new low-mass planets around the stars HD 20794, HD 85512, and HD 192310, including a system of three super-Earths and a planet with a mass of 3.6 Earth masses located at the inner edge of the habitable zone. This confirms previous indications that low-mass planets seem to be very frequent around solar-type stars, with an occurrence rate that may be higher than 30%.
This document describes the discovery and characterization of CFBDSIR2149, a late T dwarf found to have an unusually red J-K color and enhanced K-band flux. Spectroscopy with X-Shooter revealed it has a T7 spectral type with low surface gravity features, indicating it is a young substellar object. Comparison to atmospheric models suggests it has a temperature of 650-750K, surface gravity of logg=3.75-4.0, and a mass in the planetary regime of 4-7 Jupiter masses. An analysis of its proper motion finds an 87% probability it is a member of the young AB Doradus moving group, which would make it a free-floating planet with an
This document summarizes the discovery of a fourth planet orbiting the red dwarf star GJ 581. The planet, called GJ 581e, has a minimum mass of 1.9 Earth masses and orbits with a period of 3.15 days, making it the innermost planet in the system. Updated radial velocity measurements also allowed the researchers to correct the orbital period of the outermost planet GJ 581d, determining it to be 66.8 days rather than the previously reported 83 days. This revised period places GJ 581d within the star's habitable zone. The researchers conclude the GJ 581 system has 4 planets, with the detection of GJ 581e being the lowest mass exoplanet
Cosmogenic Nuclide Dating Of Sahelanthropus Tchadensis And Australopiethcus B...Kristian Pedersen
This study used cosmogenic nuclide dating to determine the ages of sedimentary units containing hominid remains at two localities in Chad - KT 12 locality in Koro Toro and TM 266 locality in Toros-Menalla. At KT 12, which contained Australopithecus bahrelghazali, authigenic 10Be/9Be dating of the sedimentary level yielded an age of 3.58 ± 0.27 Ma, consistent with an early Pliocene age estimation. At TM 266, where Sahelanthropus tchadensis was found, 28 10Be/9Be ages from the anthracotheriid unit containing the hominid remains bracketed its age between 6.8
Large heterogeneities in_comet_67_p_as_revealed_by_active_pits_from_sinkhole_...Sérgio Sacani
Em um estudo publicado online na edição da revista Nature, 18 cavidades quase circulares foram identificadas no hemisfério norte do cometa 67P/Churyumov-Gerasimenko. As cavidades tem de dezenas a centenas de metros de diâmetro e se estendem a mais de 210 metros abaixo da superfície do cometa. Essas cavidades são ativas e provavelmente criadas por um processo de sumidouro, possivelmente acompanhado por explosões.
A sonda Rosetta da ESA tem monitorado a atividade do cometa por mais de um ano, observando como seu halo de poeira e gás cresce à medida que o cometa se move para perto do Sol ao longo de sua órbita.
De uma distância de apenas centenas de quilômetros, a sonda observa um intrigante padrão de jatos de poeira sendo emitidos do núcleo enquanto eles são ejetados para o espaço.
Mas agora, graças a imagens de alta resolução da câmera de ângulo restrito da sonda, a Optical Spectroscopic and Infrared Remote Imaging System (OSIRIS), feitas de uma distância entre 10 a 30 km do centro do cometa, alguns desses jatos puderam ser rastreados de volta à superfície do cometa, chegando até a sua fonte, é a primeira vez que isso é feito e observado.
This document provides an overview and context for a study of the symbiotic star SS Leporis using interferometric imaging with the PIONIER instrument on the VLTI. Key points:
- SS Leporis is a long-period interacting binary system composed of an A star accreting material from an evolved M giant companion, presenting an "Algol paradox" where the more evolved star is less massive.
- Previous studies have not fully constrained the system morphology and characteristics. New interferometric observations with PIONIER were obtained to directly probe the inner parts of the system.
- The observations were used to perform aperture synthesis imaging and model the system as a binary surrounded by a circumbinary disc. This provides the
This document summarizes the results of a 180 ks Chandra-LETGS observation of Mrk 509 as part of a larger multi-wavelength campaign. The observation detected several absorption features in the X-ray spectrum originating from an ionized absorber, including ions with three distinct ionization degrees. The lowest ionized component is slightly redshifted and not in pressure equilibrium with the others, likely belonging to the host galaxy's interstellar medium. The other two components are outflowing at velocities of around -200 and -455 km/s. Simultaneous HST-COS observations detected 13 UV kinematic components, and at least three can be associated with the X-ray components, providing evidence that the UV and X-
The harps serach_for_southern_exoplanets_02Sérgio Sacani
The document presents an analysis of additional radial velocity measurements of the M dwarf stars Gl 433 and Gl 667C, obtained with the HARPS spectrograph. It finds:
- For Gl 433, one planet (Gl 433b) with a minimum mass of about 5.5 Earth masses and an orbital period of about 7 days. Longer period radial velocity variations are also detected, likely due to magnetic activity cycles.
- For Gl 667C, two planets are found. Gl 667Cb has a minimum mass of about 5.5 Earth masses and an orbital period of about 7 days. Gl 667Cc has a minimum mass of about 4.25 Earth masses and orbits in the habitable zone of its star with a
The document summarizes the first results from an ambitious HARPS program to detect Earth-like planets around nearby solar-type stars using high-precision radial velocity measurements. It reports the discovery of five new low-mass planets around the stars HD 20794, HD 85512, and HD 192310, including a system of three super-Earths and a planet with a mass of 3.6 Earth masses located at the inner edge of the habitable zone. This confirms previous indications that low-mass planets seem to be very frequent around solar-type stars, with an occurrence rate that may be higher than 30%.
This document describes the discovery and characterization of CFBDSIR2149, a late T dwarf found to have an unusually red J-K color and enhanced K-band flux. Spectroscopy with X-Shooter revealed it has a T7 spectral type with low surface gravity features, indicating it is a young substellar object. Comparison to atmospheric models suggests it has a temperature of 650-750K, surface gravity of logg=3.75-4.0, and a mass in the planetary regime of 4-7 Jupiter masses. An analysis of its proper motion finds an 87% probability it is a member of the young AB Doradus moving group, which would make it a free-floating planet with an
This document summarizes the discovery of a fourth planet orbiting the red dwarf star GJ 581. The planet, called GJ 581e, has a minimum mass of 1.9 Earth masses and orbits with a period of 3.15 days, making it the innermost planet in the system. Updated radial velocity measurements also allowed the researchers to correct the orbital period of the outermost planet GJ 581d, determining it to be 66.8 days rather than the previously reported 83 days. This revised period places GJ 581d within the star's habitable zone. The researchers conclude the GJ 581 system has 4 planets, with the detection of GJ 581e being the lowest mass exoplanet
Cosmogenic Nuclide Dating Of Sahelanthropus Tchadensis And Australopiethcus B...Kristian Pedersen
This study used cosmogenic nuclide dating to determine the ages of sedimentary units containing hominid remains at two localities in Chad - KT 12 locality in Koro Toro and TM 266 locality in Toros-Menalla. At KT 12, which contained Australopithecus bahrelghazali, authigenic 10Be/9Be dating of the sedimentary level yielded an age of 3.58 ± 0.27 Ma, consistent with an early Pliocene age estimation. At TM 266, where Sahelanthropus tchadensis was found, 28 10Be/9Be ages from the anthracotheriid unit containing the hominid remains bracketed its age between 6.8
Large heterogeneities in_comet_67_p_as_revealed_by_active_pits_from_sinkhole_...Sérgio Sacani
Em um estudo publicado online na edição da revista Nature, 18 cavidades quase circulares foram identificadas no hemisfério norte do cometa 67P/Churyumov-Gerasimenko. As cavidades tem de dezenas a centenas de metros de diâmetro e se estendem a mais de 210 metros abaixo da superfície do cometa. Essas cavidades são ativas e provavelmente criadas por um processo de sumidouro, possivelmente acompanhado por explosões.
A sonda Rosetta da ESA tem monitorado a atividade do cometa por mais de um ano, observando como seu halo de poeira e gás cresce à medida que o cometa se move para perto do Sol ao longo de sua órbita.
De uma distância de apenas centenas de quilômetros, a sonda observa um intrigante padrão de jatos de poeira sendo emitidos do núcleo enquanto eles são ejetados para o espaço.
Mas agora, graças a imagens de alta resolução da câmera de ângulo restrito da sonda, a Optical Spectroscopic and Infrared Remote Imaging System (OSIRIS), feitas de uma distância entre 10 a 30 km do centro do cometa, alguns desses jatos puderam ser rastreados de volta à superfície do cometa, chegando até a sua fonte, é a primeira vez que isso é feito e observado.
This document provides an overview and context for a study of the symbiotic star SS Leporis using interferometric imaging with the PIONIER instrument on the VLTI. Key points:
- SS Leporis is a long-period interacting binary system composed of an A star accreting material from an evolved M giant companion, presenting an "Algol paradox" where the more evolved star is less massive.
- Previous studies have not fully constrained the system morphology and characteristics. New interferometric observations with PIONIER were obtained to directly probe the inner parts of the system.
- The observations were used to perform aperture synthesis imaging and model the system as a binary surrounded by a circumbinary disc. This provides the
This document summarizes the results of a 180 ks Chandra-LETGS observation of Mrk 509 as part of a larger multi-wavelength campaign. The observation detected several absorption features in the X-ray spectrum originating from an ionized absorber, including ions with three distinct ionization degrees. The lowest ionized component is slightly redshifted and not in pressure equilibrium with the others, likely belonging to the host galaxy's interstellar medium. The other two components are outflowing at velocities of around -200 and -455 km/s. Simultaneous HST-COS observations detected 13 UV kinematic components, and at least three can be associated with the X-ray components, providing evidence that the UV and X-
This document summarizes a study that uses U-band photometry to determine photometric distances to young stars in the inner Galactic disk. The study focuses on the line of sight towards the Galactic longitude of 314 degrees. Photometric data is collected and calibrated using two open clusters in the field. Three groups of stars are detected at distances of 1.5, 2.5, and 5.1 kpc, which are consistent with the Carina-Sagittarius and Scutum-Crux spiral arms. The use of U-band photometry is shown to be an effective method for characterizing young star populations and making predictions about spiral structure in the Milky Way.
The herschel exploitation_of_local_galaxy_andromeda_(helga)_global_farinfrare...Sérgio Sacani
The Herschel satellite was used to observe the Andromeda Galaxy (M31) at far-infrared and submillimeter wavelengths between 100-500 microns. The observations cover an area of about 5.5 by 2.5 degrees centered on M31, the largest area ever observed for this galaxy at these wavelengths. The data reveal dust emission extending significantly beyond M31's optical radius of about 21 kpc. Specifically, annular dust structures are detected on both sides of M31 at a galactocentric distance of about 21 kpc, and two additional annular structures are detected even further out, at about 26 and 31 kpc from the center of M31. In total, the observations estimate the
Invited Seminar presented at the VIA Forum Astroparticle Physics Forum COSMOVIA
21 March 2020
http://viavca.in2p3.fr/2010c_o_s_m_o_v_i_a__forum_sd24fsdf4zerfzef4ze5f4dsq34sdteerui45788789745rt7yr68t4y54865h45g4hfg56h45df4h86d48h48t7uertujirjtiorjhuiofgrdsqgxcvfghfg5h40yhuyir/viewtopic.php?f=73&t=3705&sid=c56cbf76f87536fc4c3ff216d9edaba2
Author: O.M. Lecian
Speaker: O.M. Lecian
Abstract: The LHAASO experiment is aimed at detecting highly-energetic particles of cosmological origin within a large
range of energies.
The sensitivity of the experimental apparatus can within the frameworks of statistical fluctuations of the
background.
Acceleration and lower-energy particles can be analyzed.
The anisotropy mass composition of cosmic rays can analytically described.
The LHAASO Experiment is also suited for detecting particles of cosmological origin originated from the breach
(and/or other kinds of modifications) of particle theories paradigms comprehending other symmetry groups.
Some physical implications of anisotropies can be looked for.
The study of anisotropy distribution for particles of cosmological origin as well as the anisotropies of their velocities
both in the case of a flat Minkowskian background as well as in the case of curved space-time can be investigated,
as far as the theoretical description of the cross-section is concerned, as well as for the theoretical expressions of
such quantities to be analyzed.
The case of a geometrical phase of particles can be schematized by means of a geometrical factor.
Particular solutions are found under suitable approximations.
A comparison with the study of ellipsoidal galaxies is achieved.
The case of particles with anisotropies in velocities falling off faster than dark matter (DM) is compared.
The study of possible anisotropies in the spatial distribution of cosmological particles can therefore be described
also deriving form the interaction of cosmic particles with the gravitational field, arising at quantum distances, at
the semiclassical level and at the classical scales, within the framework of the proper description of particles
anisotropies properties.
This document reports on observations of comet 103P/Hartley 2 made by the WISE space telescope in May 2010 and additional ground-based telescopes. The WISE observations detected the comet's coma, nucleus, and dust trail. Analysis of the coma suggests dust particles larger than those observed for comet 81P/Wild 2. The extracted nucleus is estimated to be 0.6 km in radius. Emission detected at 4.6 microns may be from carbon monoxide or carbon dioxide gas. Carbon dioxide production rates are estimated to be 3.5×1024 molecules per second. The dust trail was detected with an optical depth of 9×10-10 and minimum mass of 4×1010 kg. These observations provide
The harps n-rocky_planet_search_hd219134b_transiting_rocky_planetSérgio Sacani
Usando o espectrógrafo HARPS-N acoplado ao Telescopio Nazionale Galileo no Observatório de Roque de Los Muchachos, nas Ilhas Canárias, os astrônomos descobriram três exoplanetas, classificados como Super-Terras e um gigante gasoso orbitando uma estrela próxima, chamada de HD 219134.
A HD 219134, também conhecida como HR 8832 é uma estrela do tipo anã-K de quinta magnitude, localizada a aproximadamente 21 anos-luz de distância da Terra, na constelação de Cassiopeia.
A estrela é levemente mais fria e menos massiva que o nosso sol. Ela é tão brilhante que pode ser observada a olho nu.
O sistema planetário HD 219134, abriga um planeta gigante gasoso externo e três planetas internos classificados como super-Terras, um dos quais transita em frente à estrela.
This document summarizes a presentation about lessons learned from NASA's Stardust comet sample return mission. The Stardust mission returned the first solid samples from a comet in 2006. Key lessons included the value of detailed pre-flight measurements and instrumentation that were not included due to budget and schedule constraints. Future missions could benefit from more proactive "planning for learning" approaches rather than just reactive "lessons learned." Careful recovery operations are also important for preserving samples and data about the heatshield's condition upon reentry.
Evidence for widespread hydrated minerals on asteroid (101955) BennuSérgio Sacani
Early spectral data from the Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer (OSIRISREx) mission reveal evidence for abundant hydrated minerals on the surface of near-Earth asteroid (101955) Bennu in the
form of a near-infrared absorption near 2.7 µm and thermal infrared spectral features that are most similar to those of aqueously altered CM-type carbonaceous chondrites. We observe these spectral features across the surface of Bennu, and there
is no evidence of substantial rotational variability at the spatial scales of tens to hundreds of metres observed to date. In the
visible and near-infrared (0.4 to 2.4 µm) Bennu’s spectrum appears featureless and with a blue (negative) slope, confirming
previous ground-based observations. Bennu may represent a class of objects that could have brought volatiles and organic
chemistry to Earth.
1. Scientists used stellar occultation to measure the size of the dwarf planet Eris more accurately. They found it has a radius of 1,163 km, smaller than previous estimates, though not definitively smaller than Pluto due to uncertainties in Pluto's size.
2. Surprisingly, Eris' surface was found to be very bright, which could indicate a collapsed or localized atmosphere had recently condensed onto the surface from sublimated ices as Eris moves closer to the Sun in its orbit.
3. The discovery of Eris and other large Kuiper Belt objects has challenged definitions of planets and our understanding of the outer solar system, showing Pluto is not unique and sparking debate about what constitutes
This document describes a study that determines the relative abundances of elements in the warm absorber of the active galaxy Mrk 509 using X-ray spectra from XMM-Newton and Chandra observations. The study finds relative abundances that are consistent with proto-solar values, with the exception of sulfur which is slightly underabundant. Specifically, the study measures relative abundances of carbon, nitrogen, neon, magnesium, silicon, sulfur, calcium, and iron with respect to oxygen. These abundances provide information about the enrichment processes in the host galaxy and can be compared to abundances measured in other galaxies to study abundance evolution.
This document summarizes Hubble Space Telescope ultraviolet spectroscopy of four white dwarfs known to accrete planetary debris. The spectra reveal absorption lines from a variety of metals including carbon, oxygen, aluminum, silicon, phosphorus, sulfur, chromium, iron, and nickel. Combined with optical data, between five and eleven different metals are detected in each white dwarf, indicating substantial chemical diversity in the accreted planetary debris. The abundances observed provide insights into the composition and origin of the debris, with some debris resembling bulk Earth composition and others showing evidence of melting and differentiation.
NGC 680 and NGC 5557 are early-type galaxies that were observed with deep optical imaging to study their outer morphologies. NGC 680 exhibits extended plumes and tails that appear connected to HI gas, as well as arcs and shells. NGC 5557 has a gigantic 160 kpc long narrow tail containing three star-forming objects. The features suggest that each galaxy underwent a major wet merger over 1-2 Gyr ago, with NGC 5557's merger dominating its formation history and making it a slow rotator, while NGC 680 rotates faster.
This document summarizes an observational study of 92 southern stars using near-infrared interferometry to search for hot exozodiacal dust. The study found an 11% detection rate of bright dust, with 9 confirmed and 3 tentative detections. The detection rate decreased for later spectral type stars and increased with stellar age. No correlation was found between the presence of cold dust and hot dust. Spectral analysis suggested the dust is extremely hot or emission is dominated by scattered light in most cases. The results provide insights into the prevalence and properties of dust near the habitable zones of other stars.
1) The document describes small-scale graben (extensional faults) discovered on the Moon using images from the Lunar Reconnaissance Orbiter Camera.
2) Some graben are located near lobate scarps (contractional faults), while others are found in mare basalts and in the highlands.
3) The graben crosscut small impact craters, suggesting they formed recently, within the last 50 million years. This indicates the Moon has experienced recent extensional tectonic activity.
1. INTEGRAL observations of the SNR IC443 region detected several sources, including the pulsar wind nebula (Src #5) and the enigmatic hard X-ray source Src #11.
2. JEM-X images in the 6-10 and 10-20 keV bands tentatively identified counterparts for Src #5 and Src #11. Measured fluxes from JEM-X were consistent with XMM spectra but did not provide strong constraints.
3. Optical and infrared images showed possible counterparts for Src #11, including point sources and diffuse 2MASS-Ks emission thought to originate from shocked molecular hydrogen, suggesting a correlation between X-ray and infrared emission.
The OPERA experiment measures the velocity of neutrinos produced at CERN and detected 730 km away at the Gran Sasso laboratory to high precision. To do so it must accurately measure the time of flight of neutrinos between the two sites by precisely synchronizing clocks at CERN and Gran Sasso, determining the baseline distance through geodesy, and calibrating the timing of the proton beam and neutrino detection. This allows OPERA to search for small deviations from the speed of light in the measurement of the neutrino velocity.
Stefano Sposetti and Marco Iten detected a probable lunar impact event on February 11, 2011 while monitoring the moon from two separate observatories in Switzerland. Their videos showed a flash of light on the lunar surface at 20:36:58 UTC. Analysis of the light curves and location of the flash place the impact in a region of craters near 86°W, 16°N. The editorial board of Selenology Today notes that images from the Lunar Reconnaissance Orbiter before and after the reported event can be searched to look for an impact crater at the reported coordinates.
1) The Fermi bubbles are giant gamma-ray emitting structures extending above and below the galactic center.
2) The bubbles may have been formed by periodic capture of stars by the supermassive black hole at the galactic center, releasing energy of around 3x10^52 ergs per capture.
3) This energy injection could produce very hot plasma, accelerating electrons that produce radio and gamma-ray emission through synchrotron radiation and inverse Compton scattering.
Teachable moment the japan earthquake and tsunamiSérgio Sacani
On March 11, 2011, a 9.0 magnitude earthquake struck off the coast of Honshu, Japan, generating a powerful tsunami. This was one of the largest earthquakes in Japanese history and caused widespread damage. The earthquake and tsunami highlighted Japan's vulnerability to natural disasters due to its location at the boundary of four tectonic plates.
This document presents a new preon model with three fundamental spin-1/2 preons (α, β, δ) that can combine to form nine leptons, nine quarks, and nine heavy vector bosons. The preons have charges of +e/3, -2e/3, and +e/3. Quarks and leptons are composed of combinations of one spin-1/2 preon and one spin-0 "dipreon" made of two spin-1/2 preons. This model aims to address shortcomings of the standard model such as the large number of fundamental particles and mixings between particles, through a more fundamental layer of preons with an underlying symmetry.
Vegetti et al. discovered a satellite galaxy located around a more distant elliptical galaxy acting as a gravitational lens. They were able to detect the satellite galaxy through its effect on distorting light from a background source, causing detectable "dents and blobs" in the ring of light formed by the main lens galaxy. This satellite galaxy has a mass of about 113 million solar masses, making it one of the lowest-mass satellite galaxies detected so far. The discovery provides evidence that gravitational lensing techniques can be used to find satellite galaxies beyond the Local Group and help test theories of galaxy formation and evolution.
Measurement of lmpulsive Thrust from a Closed Radio Frequency Cavity in VacuumSérgio Sacani
A vacuum test campaign evaluating the impulsive thrust performance of a tapered RF test article excited in the TM212 mode at 1,937 megahertz (MHz) has been completed. The test campaign consisted of a forward thrust phase and reverse thrust phase at less than 8 x 10-6 Torr vacuum with power scans at 40 watts, 60 watts, and 80 watts. The test campaign included a null thrust test effort to identify any mundane sources of impulsive thrust, however none were identified. Thrust data from forward, reverse, and null suggests that the system is consistently performing with a thrust to power ratio of 1.2 ± 0.1 mN/kW.
This document summarizes a study that uses U-band photometry to determine photometric distances to young stars in the inner Galactic disk. The study focuses on the line of sight towards the Galactic longitude of 314 degrees. Photometric data is collected and calibrated using two open clusters in the field. Three groups of stars are detected at distances of 1.5, 2.5, and 5.1 kpc, which are consistent with the Carina-Sagittarius and Scutum-Crux spiral arms. The use of U-band photometry is shown to be an effective method for characterizing young star populations and making predictions about spiral structure in the Milky Way.
The herschel exploitation_of_local_galaxy_andromeda_(helga)_global_farinfrare...Sérgio Sacani
The Herschel satellite was used to observe the Andromeda Galaxy (M31) at far-infrared and submillimeter wavelengths between 100-500 microns. The observations cover an area of about 5.5 by 2.5 degrees centered on M31, the largest area ever observed for this galaxy at these wavelengths. The data reveal dust emission extending significantly beyond M31's optical radius of about 21 kpc. Specifically, annular dust structures are detected on both sides of M31 at a galactocentric distance of about 21 kpc, and two additional annular structures are detected even further out, at about 26 and 31 kpc from the center of M31. In total, the observations estimate the
Invited Seminar presented at the VIA Forum Astroparticle Physics Forum COSMOVIA
21 March 2020
http://viavca.in2p3.fr/2010c_o_s_m_o_v_i_a__forum_sd24fsdf4zerfzef4ze5f4dsq34sdteerui45788789745rt7yr68t4y54865h45g4hfg56h45df4h86d48h48t7uertujirjtiorjhuiofgrdsqgxcvfghfg5h40yhuyir/viewtopic.php?f=73&t=3705&sid=c56cbf76f87536fc4c3ff216d9edaba2
Author: O.M. Lecian
Speaker: O.M. Lecian
Abstract: The LHAASO experiment is aimed at detecting highly-energetic particles of cosmological origin within a large
range of energies.
The sensitivity of the experimental apparatus can within the frameworks of statistical fluctuations of the
background.
Acceleration and lower-energy particles can be analyzed.
The anisotropy mass composition of cosmic rays can analytically described.
The LHAASO Experiment is also suited for detecting particles of cosmological origin originated from the breach
(and/or other kinds of modifications) of particle theories paradigms comprehending other symmetry groups.
Some physical implications of anisotropies can be looked for.
The study of anisotropy distribution for particles of cosmological origin as well as the anisotropies of their velocities
both in the case of a flat Minkowskian background as well as in the case of curved space-time can be investigated,
as far as the theoretical description of the cross-section is concerned, as well as for the theoretical expressions of
such quantities to be analyzed.
The case of a geometrical phase of particles can be schematized by means of a geometrical factor.
Particular solutions are found under suitable approximations.
A comparison with the study of ellipsoidal galaxies is achieved.
The case of particles with anisotropies in velocities falling off faster than dark matter (DM) is compared.
The study of possible anisotropies in the spatial distribution of cosmological particles can therefore be described
also deriving form the interaction of cosmic particles with the gravitational field, arising at quantum distances, at
the semiclassical level and at the classical scales, within the framework of the proper description of particles
anisotropies properties.
This document reports on observations of comet 103P/Hartley 2 made by the WISE space telescope in May 2010 and additional ground-based telescopes. The WISE observations detected the comet's coma, nucleus, and dust trail. Analysis of the coma suggests dust particles larger than those observed for comet 81P/Wild 2. The extracted nucleus is estimated to be 0.6 km in radius. Emission detected at 4.6 microns may be from carbon monoxide or carbon dioxide gas. Carbon dioxide production rates are estimated to be 3.5×1024 molecules per second. The dust trail was detected with an optical depth of 9×10-10 and minimum mass of 4×1010 kg. These observations provide
The harps n-rocky_planet_search_hd219134b_transiting_rocky_planetSérgio Sacani
Usando o espectrógrafo HARPS-N acoplado ao Telescopio Nazionale Galileo no Observatório de Roque de Los Muchachos, nas Ilhas Canárias, os astrônomos descobriram três exoplanetas, classificados como Super-Terras e um gigante gasoso orbitando uma estrela próxima, chamada de HD 219134.
A HD 219134, também conhecida como HR 8832 é uma estrela do tipo anã-K de quinta magnitude, localizada a aproximadamente 21 anos-luz de distância da Terra, na constelação de Cassiopeia.
A estrela é levemente mais fria e menos massiva que o nosso sol. Ela é tão brilhante que pode ser observada a olho nu.
O sistema planetário HD 219134, abriga um planeta gigante gasoso externo e três planetas internos classificados como super-Terras, um dos quais transita em frente à estrela.
This document summarizes a presentation about lessons learned from NASA's Stardust comet sample return mission. The Stardust mission returned the first solid samples from a comet in 2006. Key lessons included the value of detailed pre-flight measurements and instrumentation that were not included due to budget and schedule constraints. Future missions could benefit from more proactive "planning for learning" approaches rather than just reactive "lessons learned." Careful recovery operations are also important for preserving samples and data about the heatshield's condition upon reentry.
Evidence for widespread hydrated minerals on asteroid (101955) BennuSérgio Sacani
Early spectral data from the Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer (OSIRISREx) mission reveal evidence for abundant hydrated minerals on the surface of near-Earth asteroid (101955) Bennu in the
form of a near-infrared absorption near 2.7 µm and thermal infrared spectral features that are most similar to those of aqueously altered CM-type carbonaceous chondrites. We observe these spectral features across the surface of Bennu, and there
is no evidence of substantial rotational variability at the spatial scales of tens to hundreds of metres observed to date. In the
visible and near-infrared (0.4 to 2.4 µm) Bennu’s spectrum appears featureless and with a blue (negative) slope, confirming
previous ground-based observations. Bennu may represent a class of objects that could have brought volatiles and organic
chemistry to Earth.
1. Scientists used stellar occultation to measure the size of the dwarf planet Eris more accurately. They found it has a radius of 1,163 km, smaller than previous estimates, though not definitively smaller than Pluto due to uncertainties in Pluto's size.
2. Surprisingly, Eris' surface was found to be very bright, which could indicate a collapsed or localized atmosphere had recently condensed onto the surface from sublimated ices as Eris moves closer to the Sun in its orbit.
3. The discovery of Eris and other large Kuiper Belt objects has challenged definitions of planets and our understanding of the outer solar system, showing Pluto is not unique and sparking debate about what constitutes
This document describes a study that determines the relative abundances of elements in the warm absorber of the active galaxy Mrk 509 using X-ray spectra from XMM-Newton and Chandra observations. The study finds relative abundances that are consistent with proto-solar values, with the exception of sulfur which is slightly underabundant. Specifically, the study measures relative abundances of carbon, nitrogen, neon, magnesium, silicon, sulfur, calcium, and iron with respect to oxygen. These abundances provide information about the enrichment processes in the host galaxy and can be compared to abundances measured in other galaxies to study abundance evolution.
This document summarizes Hubble Space Telescope ultraviolet spectroscopy of four white dwarfs known to accrete planetary debris. The spectra reveal absorption lines from a variety of metals including carbon, oxygen, aluminum, silicon, phosphorus, sulfur, chromium, iron, and nickel. Combined with optical data, between five and eleven different metals are detected in each white dwarf, indicating substantial chemical diversity in the accreted planetary debris. The abundances observed provide insights into the composition and origin of the debris, with some debris resembling bulk Earth composition and others showing evidence of melting and differentiation.
NGC 680 and NGC 5557 are early-type galaxies that were observed with deep optical imaging to study their outer morphologies. NGC 680 exhibits extended plumes and tails that appear connected to HI gas, as well as arcs and shells. NGC 5557 has a gigantic 160 kpc long narrow tail containing three star-forming objects. The features suggest that each galaxy underwent a major wet merger over 1-2 Gyr ago, with NGC 5557's merger dominating its formation history and making it a slow rotator, while NGC 680 rotates faster.
This document summarizes an observational study of 92 southern stars using near-infrared interferometry to search for hot exozodiacal dust. The study found an 11% detection rate of bright dust, with 9 confirmed and 3 tentative detections. The detection rate decreased for later spectral type stars and increased with stellar age. No correlation was found between the presence of cold dust and hot dust. Spectral analysis suggested the dust is extremely hot or emission is dominated by scattered light in most cases. The results provide insights into the prevalence and properties of dust near the habitable zones of other stars.
1) The document describes small-scale graben (extensional faults) discovered on the Moon using images from the Lunar Reconnaissance Orbiter Camera.
2) Some graben are located near lobate scarps (contractional faults), while others are found in mare basalts and in the highlands.
3) The graben crosscut small impact craters, suggesting they formed recently, within the last 50 million years. This indicates the Moon has experienced recent extensional tectonic activity.
1. INTEGRAL observations of the SNR IC443 region detected several sources, including the pulsar wind nebula (Src #5) and the enigmatic hard X-ray source Src #11.
2. JEM-X images in the 6-10 and 10-20 keV bands tentatively identified counterparts for Src #5 and Src #11. Measured fluxes from JEM-X were consistent with XMM spectra but did not provide strong constraints.
3. Optical and infrared images showed possible counterparts for Src #11, including point sources and diffuse 2MASS-Ks emission thought to originate from shocked molecular hydrogen, suggesting a correlation between X-ray and infrared emission.
The OPERA experiment measures the velocity of neutrinos produced at CERN and detected 730 km away at the Gran Sasso laboratory to high precision. To do so it must accurately measure the time of flight of neutrinos between the two sites by precisely synchronizing clocks at CERN and Gran Sasso, determining the baseline distance through geodesy, and calibrating the timing of the proton beam and neutrino detection. This allows OPERA to search for small deviations from the speed of light in the measurement of the neutrino velocity.
Stefano Sposetti and Marco Iten detected a probable lunar impact event on February 11, 2011 while monitoring the moon from two separate observatories in Switzerland. Their videos showed a flash of light on the lunar surface at 20:36:58 UTC. Analysis of the light curves and location of the flash place the impact in a region of craters near 86°W, 16°N. The editorial board of Selenology Today notes that images from the Lunar Reconnaissance Orbiter before and after the reported event can be searched to look for an impact crater at the reported coordinates.
1) The Fermi bubbles are giant gamma-ray emitting structures extending above and below the galactic center.
2) The bubbles may have been formed by periodic capture of stars by the supermassive black hole at the galactic center, releasing energy of around 3x10^52 ergs per capture.
3) This energy injection could produce very hot plasma, accelerating electrons that produce radio and gamma-ray emission through synchrotron radiation and inverse Compton scattering.
Teachable moment the japan earthquake and tsunamiSérgio Sacani
On March 11, 2011, a 9.0 magnitude earthquake struck off the coast of Honshu, Japan, generating a powerful tsunami. This was one of the largest earthquakes in Japanese history and caused widespread damage. The earthquake and tsunami highlighted Japan's vulnerability to natural disasters due to its location at the boundary of four tectonic plates.
This document presents a new preon model with three fundamental spin-1/2 preons (α, β, δ) that can combine to form nine leptons, nine quarks, and nine heavy vector bosons. The preons have charges of +e/3, -2e/3, and +e/3. Quarks and leptons are composed of combinations of one spin-1/2 preon and one spin-0 "dipreon" made of two spin-1/2 preons. This model aims to address shortcomings of the standard model such as the large number of fundamental particles and mixings between particles, through a more fundamental layer of preons with an underlying symmetry.
Vegetti et al. discovered a satellite galaxy located around a more distant elliptical galaxy acting as a gravitational lens. They were able to detect the satellite galaxy through its effect on distorting light from a background source, causing detectable "dents and blobs" in the ring of light formed by the main lens galaxy. This satellite galaxy has a mass of about 113 million solar masses, making it one of the lowest-mass satellite galaxies detected so far. The discovery provides evidence that gravitational lensing techniques can be used to find satellite galaxies beyond the Local Group and help test theories of galaxy formation and evolution.
Measurement of lmpulsive Thrust from a Closed Radio Frequency Cavity in VacuumSérgio Sacani
A vacuum test campaign evaluating the impulsive thrust performance of a tapered RF test article excited in the TM212 mode at 1,937 megahertz (MHz) has been completed. The test campaign consisted of a forward thrust phase and reverse thrust phase at less than 8 x 10-6 Torr vacuum with power scans at 40 watts, 60 watts, and 80 watts. The test campaign included a null thrust test effort to identify any mundane sources of impulsive thrust, however none were identified. Thrust data from forward, reverse, and null suggests that the system is consistently performing with a thrust to power ratio of 1.2 ± 0.1 mN/kW.
Detection of highvelocity_material_from_the_win_wind_collision_zone_of_eta_ca...Sérgio Sacani
This document reports on observations of the Eta Carinae binary system using infrared spectroscopy from 2008-2009 and archival ultraviolet and optical data. It detects high-velocity material of up to -1900 km/s in He I absorption during the 2009 periastron passage, as well as up to -2100 km/s in Si IV absorption in earlier data. Lower ionization lines only show absorption up to -1200 km/s, indicating the high-velocity material is faster and more ionized than the primary star's wind. Additional observations over multiple cycles detect high-velocity He I absorption near periastron. The high-velocity material likely originates in the wind collision zone 15-45 AU from the primary star.
1. This document describes a multiwavelength campaign on the Seyfert 1 galaxy Mrk 509 using five satellites and two ground-based facilities.
2. The campaign aims to study several open questions about active galactic nuclei (AGN), including the location and physics of outflows from AGN, the nature of continuum emission, the geometry and physical state of the X-ray broad emission line region, and the Fe-K line complex.
3. The observations cover more than five decades in frequency, from 2 μm to 200 keV, and include a simultaneous set of deep XMM-Newton and INTEGRAL observations over seven weeks. This allows the authors to disentangle different components and study time variability
This paper analyzes Spitzer observations of the Eagle Nebula to study the energetics and evolution of dust. The observations show a shell of emission within the nebula at mid-IR wavelengths that is distinct from the morphology at longer wavelengths. Spectral energy distributions are measured across the nebula and modeled to constrain dust properties and heating sources. Two possible interpretations are proposed for the nature of the mid-IR shell: 1) dust processing in shocks driven by stellar winds, or 2) emission from a hot plasma where dust is collisionally heated. The goal is to better understand dust evolution in massive star forming regions.
This document summarizes an 8-year survey using the HARPS spectrograph to detect super-Earth and Neptune-mass planets around solar-type stars. Over 50% of solar-type stars were found to harbor at least one planet within 100 days. The mass distribution of super-Earths and Neptune-mass planets increases sharply from 30-15 Earth masses. Most of these planets belong to multi-planetary systems and have orbital eccentricities under 0.45. In contrast, giant planets are more common around metal-rich stars and can have eccentricities over 0.9. The precision of HARPS enables detection of planets in the habitable zones of solar-type stars.
An earth sized_planet_with_an_earth_sized_densitySérgio Sacani
1) Researchers observed the exoplanet Kepler-78b using the HARPS-N spectrograph to measure its mass.
2) They measured Kepler-78b's mass to be 1.86 Earth masses, giving it a density similar to Earth, implying a rocky composition of iron and rock.
3) The small size of Kepler-78b makes it the smallest exoplanet yet measured for both mass and radius, establishing that Earth-sized planets can be terrestrial.
A dust obscured_massive_maximum_starburst_galaxy_at_a_redshift_634Sérgio Sacani
This document summarizes the discovery of a massive, intensely star-forming galaxy located at a redshift of 6.34, approximately 880 million years after the Big Bang. Observations revealed a suite of molecular and atomic emission and absorption lines that unambiguously determined the galaxy's redshift. Analysis shows the galaxy contains over 100 billion solar masses of chemically evolved interstellar medium, constituting at least 40% of its baryonic mass. It is forming new stars at a rate over 2,000 times that of the Milky Way, making it a "maximum starburst" galaxy. Despite an overall decline in cosmic star formation at the highest redshifts, this discovery shows that environments capable of hosting the most massive starbursts existed very early
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
1. VFTS 682 is a very massive star located 29 pc in projection from the young massive cluster R136 in the Tarantula Nebula of the LMC.
2. Spectral modeling finds it has an unusually high luminosity of log(L/L) = 6.5, corresponding to a present-day mass of ~150 solar masses.
3. Its isolation and mass pose the question of whether it formed in situ, which would profoundly impact theories of massive star formation, or if it was ejected from R136, making it the most massive runaway star known.
This document reports the discovery of the central star of the planetary nebula IC 4663, which exhibits spectral properties that mimic a nitrogen-rich Wolf-Rayet star of spectral type [WN3]. This makes it the first unambiguous case of a planetary nebula central star taking on the properties of a Wolf-Rayet star. The central star is dominated by broad helium and nitrogen emission lines. The surrounding nebula is definitively a planetary nebula based on its morphology and chemical abundances. The discovery provides evidence for an alternative evolutionary pathway for some hydrogen-deficient, helium-rich post-asymptotic giant branch stars.
No global pluto_like_atmosphere_on_dwarf_planet_makemake_from_a_stellar_occul...Sérgio Sacani
1. A stellar occultation event was observed involving the dwarf planet Makemake on April 23, 2011 using multiple telescopes.
2. Analysis of the light curves from the event showed abrupt disappearances and reappearances of the star, indicating Makemake has no global atmosphere at an upper limit of 4-12 nanobar surface pressure.
3. The occultation data was used to determine Makemake has dimensions of 1,430±9 km by 1,502±45 km, implying a high geometric albedo of 0.77±0.03. This rules out a low density and suggests Makemake is in hydrostatic equilibrium as an oblate spheroid.
The long period_galactic_cepheid_rs_puppisSérgio Sacani
This document summarizes an observational study that uses light echoes to determine the geometric distance to the Cepheid variable star RS Puppis. Images of RS Puppis and its surrounding nebula were taken over multiple epochs with the ESO NTT telescope to track the progression of light variations within the nebula. Photometric measurements of the phase lag in several nebula regions were used to derive a geometric distance of 1,992 ± 28 parsecs to RS Puppis, one of the most accurate distances yet measured to a Cepheid variable star.
1. The document describes observations of the Seyfert-1 galaxy Mrk 509 using XMM-Newton and Swift.
2. It analyzes the optical-UV and X-ray variability over a 100 day monitoring campaign with a few day resolution.
3. The results suggest that on these timescales, the soft X-ray excess in Mrk 509 is produced by warm Comptonization of thermal optical-UV photons from the accretion disk by a warm, optically thick corona surrounding the inner disk regions.
A candidate super-Earth planet orbiting near the snow line of Barnard’s starSérgio Sacani
This document summarizes the discovery of a candidate super-Earth planet orbiting Barnard's star. Analysis of over 20 years of radial velocity measurements revealed a periodic signal of 233 days, attributed to a planet with a minimum mass of 3.2 Earth masses in a near-circular orbit near the star's snow line. Long-term monitoring also detected a possible second signal with a period over 6,000 days, which could be from a more distant planet or stellar magnetic activity cycle. Independent photometric and spectroscopic monitoring ruled out stellar activity as the cause of the 233-day signal. This candidate planet has one of the lowest minimum masses detected around an M dwarf star.
A population of_fast_radio_bursts_ar_cosmological_distancesSérgio Sacani
1) Four fast radio bursts (FRBs) lasting only a few milliseconds were detected in a radio survey of the high Galactic latitude sky.
2) The bursts' properties indicate they are of celestial rather than terrestrial origin and likely originate from cosmological distances of 0.5 to 3 billion light years.
3) No coincident x-ray or gamma-ray signals were found associated with the bursts. Characterizing the population of FRBs could help determine the baryonic content of the universe.
Artigo que descreve a descoberta do exoplaneta Kepler-432b, um exoplaneta mais massivo que Júpiter que orbita uma estrela gigante vermelha bem próximo e numa órbita extremamente alongada.
Visible spectra of (474640) 2004 VN112–2013 RF98 with OSIRIS at the 10.4 m GT...Sérgio Sacani
The existence of significant anisotropies in the distributions of the directions of perihelia and
orbital poles of the known extreme trans-Neptunian objects (ETNOs) has been used to claim
that trans-Plutonian planets may exist. Among the known ETNOs, the pair (474640) 2004
VN112–2013 RF98 stands out. Their orbital poles and the directions of their perihelia and their
velocities at perihelion/aphelion are separated by a few degrees, but orbital similarity does
not necessarily imply common physical origin. In an attempt to unravel their physical nature,
visible spectroscopy of both targets was obtained using the OSIRIS camera-spectrograph at the
10.4 m Gran Telescopio Canarias (GTC). From the spectral analysis, we find that 474640–2013
RF98 have similar spectral slopes (12 versus 15 per cent/0.1 µm), very different from Sedna’s
but compatible with those of (148209) 2000 CR105 and 2012 VP113. These five ETNOs belong
to the group of seven linked to the Planet Nine hypothesis. A dynamical pathway consistent
with these findings is dissociation of a binary asteroid during a close encounter with a planet
and we confirm its plausibility using N-body simulations. We thus conclude that both the
dynamical and spectroscopic properties of 474640–2013 RF98 favour a genetic link and their
current orbits suggest that the pair was kicked by a perturber near aphelion
A herschel and_apex_census_of_the_reddest_sources_in_orion_searching_for_the_...Sérgio Sacani
This document summarizes a study that uses Herschel and APEX data to identify the reddest, youngest protostar candidates in the Orion molecular clouds. 55 new protostar candidates are detected at 70 and 160 microns that were too faint or undetected at 24 microns in previous Spitzer data. The 11 reddest candidates with log(70 micron flux / 24 micron flux) > 1.65 are considered reliable protostars, while the remaining 44 have less extreme colors and higher contamination potential. Combining these with previously known protostars yields 18 sources called PACS Bright Red sources (PBRs) with the reddest colors. Analysis finds the PBRs have properties of very young Class 0 sources like
This document reports on spectroscopic observations of z-band dropout galaxy candidates in the NTT Deep Field. Two galaxies are confirmed to be at redshift ~6.7 based on detected Lyman-alpha emission lines. For NTTDF-474, a faint line is detected at 9270 Angstroms, identified as Lyman-alpha at z=6.623. For NTTDF-1917, an emission line is seen at 8415 Angstroms, which may be Lyman-alpha or H-beta. No significant features were found for the other candidates. These results provide further evidence of galaxy populations in the early universe approaching the epoch of reionization.
This document summarizes the discovery of seven temperate terrestrial planets orbiting the nearby ultracool dwarf star TRAPPIST-1. Through extensive photometric monitoring from both ground-based telescopes and the Spitzer Space Telescope, the researchers detected multiple transiting planets with orbital periods between 1.5 and 12.3 days. Analysis of the transit light curves revealed four additional planets (TRAPPIST-1d, e, f, and g), in addition to the three initially reported. Dynamical modeling suggests the six inner planets have rocky compositions and near-resonant orbits, indicating they likely migrated inward over time. The seven planets have equilibrium temperatures low enough to possibly support liquid water on their surfaces.
Similar to The harps search_for_southern_exoplanets_01 (20)
Compositions of iron-meteorite parent bodies constrainthe structure of the pr...Sérgio Sacani
Magmatic iron-meteorite parent bodies are the earliest planetesimals in the Solar System,and they preserve information about conditions and planet-forming processes in thesolar nebula. In this study, we include comprehensive elemental compositions andfractional-crystallization modeling for iron meteorites from the cores of five differenti-ated asteroids from the inner Solar System. Together with previous results of metalliccores from the outer Solar System, we conclude that asteroidal cores from the outerSolar System have smaller sizes, elevated siderophile-element abundances, and simplercrystallization processes than those from the inner Solar System. These differences arerelated to the formation locations of the parent asteroids because the solar protoplane-tary disk varied in redox conditions, elemental distributions, and dynamics at differentheliocentric distances. Using highly siderophile-element data from iron meteorites, wereconstruct the distribution of calcium-aluminum-rich inclusions (CAIs) across theprotoplanetary disk within the first million years of Solar-System history. CAIs, the firstsolids to condense in the Solar System, formed close to the Sun. They were, however,concentrated within the outer disk and depleted within the inner disk. Future modelsof the structure and evolution of the protoplanetary disk should account for this dis-tribution pattern of CAIs.
Signatures of wave erosion in Titan’s coastsSérgio Sacani
The shorelines of Titan’s hydrocarbon seas trace flooded erosional landforms such as river valleys; however, it isunclear whether coastal erosion has subsequently altered these shorelines. Spacecraft observations and theo-retical models suggest that wind may cause waves to form on Titan’s seas, potentially driving coastal erosion,but the observational evidence of waves is indirect, and the processes affecting shoreline evolution on Titanremain unknown. No widely accepted framework exists for using shoreline morphology to quantitatively dis-cern coastal erosion mechanisms, even on Earth, where the dominant mechanisms are known. We combinelandscape evolution models with measurements of shoreline shape on Earth to characterize how differentcoastal erosion mechanisms affect shoreline morphology. Applying this framework to Titan, we find that theshorelines of Titan’s seas are most consistent with flooded landscapes that subsequently have been eroded bywaves, rather than a uniform erosional process or no coastal erosion, particularly if wave growth saturates atfetch lengths of tens of kilometers.
SDSS1335+0728: The awakening of a ∼ 106M⊙ black hole⋆Sérgio Sacani
Context. The early-type galaxy SDSS J133519.91+072807.4 (hereafter SDSS1335+0728), which had exhibited no prior optical variations during the preceding two decades, began showing significant nuclear variability in the Zwicky Transient Facility (ZTF) alert stream from December 2019 (as ZTF19acnskyy). This variability behaviour, coupled with the host-galaxy properties, suggests that SDSS1335+0728 hosts a ∼ 106M⊙ black hole (BH) that is currently in the process of ‘turning on’. Aims. We present a multi-wavelength photometric analysis and spectroscopic follow-up performed with the aim of better understanding the origin of the nuclear variations detected in SDSS1335+0728. Methods. We used archival photometry (from WISE, 2MASS, SDSS, GALEX, eROSITA) and spectroscopic data (from SDSS and LAMOST) to study the state of SDSS1335+0728 prior to December 2019, and new observations from Swift, SOAR/Goodman, VLT/X-shooter, and Keck/LRIS taken after its turn-on to characterise its current state. We analysed the variability of SDSS1335+0728 in the X-ray/UV/optical/mid-infrared range, modelled its spectral energy distribution prior to and after December 2019, and studied the evolution of its UV/optical spectra. Results. From our multi-wavelength photometric analysis, we find that: (a) since 2021, the UV flux (from Swift/UVOT observations) is four times brighter than the flux reported by GALEX in 2004; (b) since June 2022, the mid-infrared flux has risen more than two times, and the W1−W2 WISE colour has become redder; and (c) since February 2024, the source has begun showing X-ray emission. From our spectroscopic follow-up, we see that (i) the narrow emission line ratios are now consistent with a more energetic ionising continuum; (ii) broad emission lines are not detected; and (iii) the [OIII] line increased its flux ∼ 3.6 years after the first ZTF alert, which implies a relatively compact narrow-line-emitting region. Conclusions. We conclude that the variations observed in SDSS1335+0728 could be either explained by a ∼ 106M⊙ AGN that is just turning on or by an exotic tidal disruption event (TDE). If the former is true, SDSS1335+0728 is one of the strongest cases of an AGNobserved in the process of activating. If the latter were found to be the case, it would correspond to the longest and faintest TDE ever observed (or another class of still unknown nuclear transient). Future observations of SDSS1335+0728 are crucial to further understand its behaviour. Key words. galaxies: active– accretion, accretion discs– galaxies: individual: SDSS J133519.91+072807.4
Discovery of An Apparent Red, High-Velocity Type Ia Supernova at 𝐳 = 2.9 wi...Sérgio Sacani
We present the JWST discovery of SN 2023adsy, a transient object located in a host galaxy JADES-GS
+
53.13485
−
27.82088
with a host spectroscopic redshift of
2.903
±
0.007
. The transient was identified in deep James Webb Space Telescope (JWST)/NIRCam imaging from the JWST Advanced Deep Extragalactic Survey (JADES) program. Photometric and spectroscopic followup with NIRCam and NIRSpec, respectively, confirm the redshift and yield UV-NIR light-curve, NIR color, and spectroscopic information all consistent with a Type Ia classification. Despite its classification as a likely SN Ia, SN 2023adsy is both fairly red (
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(
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−
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)
∼
0.9
) despite a host galaxy with low-extinction and has a high Ca II velocity (
19
,
000
±
2
,
000
km/s) compared to the general population of SNe Ia. While these characteristics are consistent with some Ca-rich SNe Ia, particularly SN 2016hnk, SN 2023adsy is intrinsically brighter than the low-
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Ca-rich population. Although such an object is too red for any low-
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cosmological sample, we apply a fiducial standardization approach to SN 2023adsy and find that the SN 2023adsy luminosity distance measurement is in excellent agreement (
≲
1
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) with
Λ
CDM. Therefore unlike low-
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Ca-rich SNe Ia, SN 2023adsy is standardizable and gives no indication that SN Ia standardized luminosities change significantly with redshift. A larger sample of distant SNe Ia is required to determine if SN Ia population characteristics at high-
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truly diverge from their low-
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counterparts, and to confirm that standardized luminosities nevertheless remain constant with redshift.
Evidence of Jet Activity from the Secondary Black Hole in the OJ 287 Binary S...Sérgio Sacani
Wereport the study of a huge optical intraday flare on 2021 November 12 at 2 a.m. UT in the blazar OJ287. In the binary black hole model, it is associated with an impact of the secondary black hole on the accretion disk of the primary. Our multifrequency observing campaign was set up to search for such a signature of the impact based on a prediction made 8 yr earlier. The first I-band results of the flare have already been reported by Kishore et al. (2024). Here we combine these data with our monitoring in the R-band. There is a big change in the R–I spectral index by 1.0 ±0.1 between the normal background and the flare, suggesting a new component of radiation. The polarization variation during the rise of the flare suggests the same. The limits on the source size place it most reasonably in the jet of the secondary BH. We then ask why we have not seen this phenomenon before. We show that OJ287 was never before observed with sufficient sensitivity on the night when the flare should have happened according to the binary model. We also study the probability that this flare is just an oversized example of intraday variability using the Krakow data set of intense monitoring between 2015 and 2023. We find that the occurrence of a flare of this size and rapidity is unlikely. In machine-readable Tables 1 and 2, we give the full orbit-linked historical light curve of OJ287 as well as the dense monitoring sample of Krakow.
Candidate young stellar objects in the S-cluster: Kinematic analysis of a sub...Sérgio Sacani
Context. The observation of several L-band emission sources in the S cluster has led to a rich discussion of their nature. However, a definitive answer to the classification of the dusty objects requires an explanation for the detection of compact Doppler-shifted Brγ emission. The ionized hydrogen in combination with the observation of mid-infrared L-band continuum emission suggests that most of these sources are embedded in a dusty envelope. These embedded sources are part of the S-cluster, and their relationship to the S-stars is still under debate. To date, the question of the origin of these two populations has been vague, although all explanations favor migration processes for the individual cluster members. Aims. This work revisits the S-cluster and its dusty members orbiting the supermassive black hole SgrA* on bound Keplerian orbits from a kinematic perspective. The aim is to explore the Keplerian parameters for patterns that might imply a nonrandom distribution of the sample. Additionally, various analytical aspects are considered to address the nature of the dusty sources. Methods. Based on the photometric analysis, we estimated the individual H−K and K−L colors for the source sample and compared the results to known cluster members. The classification revealed a noticeable contrast between the S-stars and the dusty sources. To fit the flux-density distribution, we utilized the radiative transfer code HYPERION and implemented a young stellar object Class I model. We obtained the position angle from the Keplerian fit results; additionally, we analyzed the distribution of the inclinations and the longitudes of the ascending node. Results. The colors of the dusty sources suggest a stellar nature consistent with the spectral energy distribution in the near and midinfrared domains. Furthermore, the evaporation timescales of dusty and gaseous clumps in the vicinity of SgrA* are much shorter ( 2yr) than the epochs covered by the observations (≈15yr). In addition to the strong evidence for the stellar classification of the D-sources, we also find a clear disk-like pattern following the arrangements of S-stars proposed in the literature. Furthermore, we find a global intrinsic inclination for all dusty sources of 60 ± 20◦, implying a common formation process. Conclusions. The pattern of the dusty sources manifested in the distribution of the position angles, inclinations, and longitudes of the ascending node strongly suggests two different scenarios: the main-sequence stars and the dusty stellar S-cluster sources share a common formation history or migrated with a similar formation channel in the vicinity of SgrA*. Alternatively, the gravitational influence of SgrA* in combination with a massive perturber, such as a putative intermediate mass black hole in the IRS 13 cluster, forces the dusty objects and S-stars to follow a particular orbital arrangement. Key words. stars: black holes– stars: formation– Galaxy: center– galaxies: star formation
JAMES WEBB STUDY THE MASSIVE BLACK HOLE SEEDSSérgio Sacani
The pathway(s) to seeding the massive black holes (MBHs) that exist at the heart of galaxies in the present and distant Universe remains an unsolved problem. Here we categorise, describe and quantitatively discuss the formation pathways of both light and heavy seeds. We emphasise that the most recent computational models suggest that rather than a bimodal-like mass spectrum between light and heavy seeds with light at one end and heavy at the other that instead a continuum exists. Light seeds being more ubiquitous and the heavier seeds becoming less and less abundant due the rarer environmental conditions required for their formation. We therefore examine the different mechanisms that give rise to different seed mass spectrums. We show how and why the mechanisms that produce the heaviest seeds are also among the rarest events in the Universe and are hence extremely unlikely to be the seeds for the vast majority of the MBH population. We quantify, within the limits of the current large uncertainties in the seeding processes, the expected number densities of the seed mass spectrum. We argue that light seeds must be at least 103 to 105 times more numerous than heavy seeds to explain the MBH population as a whole. Based on our current understanding of the seed population this makes heavy seeds (Mseed > 103 M⊙) a significantly more likely pathway given that heavy seeds have an abundance pattern than is close to and likely in excess of 10−4 compared to light seeds. Finally, we examine the current state-of-the-art in numerical calculations and recent observations and plot a path forward for near-future advances in both domains.
Anti-Universe And Emergent Gravity and the Dark UniverseSérgio Sacani
Recent theoretical progress indicates that spacetime and gravity emerge together from the entanglement structure of an underlying microscopic theory. These ideas are best understood in Anti-de Sitter space, where they rely on the area law for entanglement entropy. The extension to de Sitter space requires taking into account the entropy and temperature associated with the cosmological horizon. Using insights from string theory, black hole physics and quantum information theory we argue that the positive dark energy leads to a thermal volume law contribution to the entropy that overtakes the area law precisely at the cosmological horizon. Due to the competition between area and volume law entanglement the microscopic de Sitter states do not thermalise at sub-Hubble scales: they exhibit memory effects in the form of an entropy displacement caused by matter. The emergent laws of gravity contain an additional ‘dark’ gravitational force describing the ‘elastic’ response due to the entropy displacement. We derive an estimate of the strength of this extra force in terms of the baryonic mass, Newton’s constant and the Hubble acceleration scale a0 = cH0, and provide evidence for the fact that this additional ‘dark gravity force’ explains the observed phenomena in galaxies and clusters currently attributed to dark matter.
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.
The Microsoft 365 Migration Tutorial For Beginner.pptxoperationspcvita
This presentation will help you understand the power of Microsoft 365. However, we have mentioned every productivity app included in Office 365. Additionally, we have suggested the migration situation related to Office 365 and how we can help you.
You can also read: https://www.systoolsgroup.com/updates/office-365-tenant-to-tenant-migration-step-by-step-complete-guide/
Dandelion Hashtable: beyond billion requests per second on a commodity serverAntonios Katsarakis
This slide deck presents DLHT, a concurrent in-memory hashtable. Despite efforts to optimize hashtables, that go as far as sacrificing core functionality, state-of-the-art designs still incur multiple memory accesses per request and block request processing in three cases. First, most hashtables block while waiting for data to be retrieved from memory. Second, open-addressing designs, which represent the current state-of-the-art, either cannot free index slots on deletes or must block all requests to do so. Third, index resizes block every request until all objects are copied to the new index. Defying folklore wisdom, DLHT forgoes open-addressing and adopts a fully-featured and memory-aware closed-addressing design based on bounded cache-line-chaining. This design offers lock-free index operations and deletes that free slots instantly, (2) completes most requests with a single memory access, (3) utilizes software prefetching to hide memory latencies, and (4) employs a novel non-blocking and parallel resizing. In a commodity server and a memory-resident workload, DLHT surpasses 1.6B requests per second and provides 3.5x (12x) the throughput of the state-of-the-art closed-addressing (open-addressing) resizable hashtable on Gets (Deletes).
zkStudyClub - LatticeFold: A Lattice-based Folding Scheme and its Application...Alex Pruden
Folding is a recent technique for building efficient recursive SNARKs. Several elegant folding protocols have been proposed, such as Nova, Supernova, Hypernova, Protostar, and others. However, all of them rely on an additively homomorphic commitment scheme based on discrete log, and are therefore not post-quantum secure. In this work we present LatticeFold, the first lattice-based folding protocol based on the Module SIS problem. This folding protocol naturally leads to an efficient recursive lattice-based SNARK and an efficient PCD scheme. LatticeFold supports folding low-degree relations, such as R1CS, as well as high-degree relations, such as CCS. The key challenge is to construct a secure folding protocol that works with the Ajtai commitment scheme. The difficulty, is ensuring that extracted witnesses are low norm through many rounds of folding. We present a novel technique using the sumcheck protocol to ensure that extracted witnesses are always low norm no matter how many rounds of folding are used. Our evaluation of the final proof system suggests that it is as performant as Hypernova, while providing post-quantum security.
Paper Link: https://eprint.iacr.org/2024/257
What is an RPA CoE? Session 1 – CoE VisionDianaGray10
In the first session, we will review the organization's vision and how this has an impact on the COE Structure.
Topics covered:
• The role of a steering committee
• How do the organization’s priorities determine CoE Structure?
Speaker:
Chris Bolin, Senior Intelligent Automation Architect Anika Systems
For the full video of this presentation, please visit: https://www.edge-ai-vision.com/2024/06/temporal-event-neural-networks-a-more-efficient-alternative-to-the-transformer-a-presentation-from-brainchip/
Chris Jones, Director of Product Management at BrainChip , presents the “Temporal Event Neural Networks: A More Efficient Alternative to the Transformer” tutorial at the May 2024 Embedded Vision Summit.
The expansion of AI services necessitates enhanced computational capabilities on edge devices. Temporal Event Neural Networks (TENNs), developed by BrainChip, represent a novel and highly efficient state-space network. TENNs demonstrate exceptional proficiency in handling multi-dimensional streaming data, facilitating advancements in object detection, action recognition, speech enhancement and language model/sequence generation. Through the utilization of polynomial-based continuous convolutions, TENNs streamline models, expedite training processes and significantly diminish memory requirements, achieving notable reductions of up to 50x in parameters and 5,000x in energy consumption compared to prevailing methodologies like transformers.
Integration with BrainChip’s Akida neuromorphic hardware IP further enhances TENNs’ capabilities, enabling the realization of highly capable, portable and passively cooled edge devices. This presentation delves into the technical innovations underlying TENNs, presents real-world benchmarks, and elucidates how this cutting-edge approach is positioned to revolutionize edge AI across diverse applications.
Building Production Ready Search Pipelines with Spark and MilvusZilliz
Spark is the widely used ETL tool for processing, indexing and ingesting data to serving stack for search. Milvus is the production-ready open-source vector database. In this talk we will show how to use Spark to process unstructured data to extract vector representations, and push the vectors to Milvus vector database for search serving.
Digital Banking in the Cloud: How Citizens Bank Unlocked Their MainframePrecisely
Inconsistent user experience and siloed data, high costs, and changing customer expectations – Citizens Bank was experiencing these challenges while it was attempting to deliver a superior digital banking experience for its clients. Its core banking applications run on the mainframe and Citizens was using legacy utilities to get the critical mainframe data to feed customer-facing channels, like call centers, web, and mobile. Ultimately, this led to higher operating costs (MIPS), delayed response times, and longer time to market.
Ever-changing customer expectations demand more modern digital experiences, and the bank needed to find a solution that could provide real-time data to its customer channels with low latency and operating costs. Join this session to learn how Citizens is leveraging Precisely to replicate mainframe data to its customer channels and deliver on their “modern digital bank” experiences.
For the full video of this presentation, please visit: https://www.edge-ai-vision.com/2024/06/how-axelera-ai-uses-digital-compute-in-memory-to-deliver-fast-and-energy-efficient-computer-vision-a-presentation-from-axelera-ai/
Bram Verhoef, Head of Machine Learning at Axelera AI, presents the “How Axelera AI Uses Digital Compute-in-memory to Deliver Fast and Energy-efficient Computer Vision” tutorial at the May 2024 Embedded Vision Summit.
As artificial intelligence inference transitions from cloud environments to edge locations, computer vision applications achieve heightened responsiveness, reliability and privacy. This migration, however, introduces the challenge of operating within the stringent confines of resource constraints typical at the edge, including small form factors, low energy budgets and diminished memory and computational capacities. Axelera AI addresses these challenges through an innovative approach of performing digital computations within memory itself. This technique facilitates the realization of high-performance, energy-efficient and cost-effective computer vision capabilities at the thin and thick edge, extending the frontier of what is achievable with current technologies.
In this presentation, Verhoef unveils his company’s pioneering chip technology and demonstrates its capacity to deliver exceptional frames-per-second performance across a range of standard computer vision networks typical of applications in security, surveillance and the industrial sector. This shows that advanced computer vision can be accessible and efficient, even at the very edge of our technological ecosystem.
Generating privacy-protected synthetic data using Secludy and MilvusZilliz
During this demo, the founders of Secludy will demonstrate how their system utilizes Milvus to store and manipulate embeddings for generating privacy-protected synthetic data. Their approach not only maintains the confidentiality of the original data but also enhances the utility and scalability of LLMs under privacy constraints. Attendees, including machine learning engineers, data scientists, and data managers, will witness first-hand how Secludy's integration with Milvus empowers organizations to harness the power of LLMs securely and efficiently.
5th LF Energy Power Grid Model Meet-up SlidesDanBrown980551
5th Power Grid Model Meet-up
It is with great pleasure that we extend to you an invitation to the 5th Power Grid Model Meet-up, scheduled for 6th June 2024. This event will adopt a hybrid format, allowing participants to join us either through an online Mircosoft Teams session or in person at TU/e located at Den Dolech 2, Eindhoven, Netherlands. The meet-up will be hosted by Eindhoven University of Technology (TU/e), a research university specializing in engineering science & technology.
Power Grid Model
The global energy transition is placing new and unprecedented demands on Distribution System Operators (DSOs). Alongside upgrades to grid capacity, processes such as digitization, capacity optimization, and congestion management are becoming vital for delivering reliable services.
Power Grid Model is an open source project from Linux Foundation Energy and provides a calculation engine that is increasingly essential for DSOs. It offers a standards-based foundation enabling real-time power systems analysis, simulations of electrical power grids, and sophisticated what-if analysis. In addition, it enables in-depth studies and analysis of the electrical power grid’s behavior and performance. This comprehensive model incorporates essential factors such as power generation capacity, electrical losses, voltage levels, power flows, and system stability.
Power Grid Model is currently being applied in a wide variety of use cases, including grid planning, expansion, reliability, and congestion studies. It can also help in analyzing the impact of renewable energy integration, assessing the effects of disturbances or faults, and developing strategies for grid control and optimization.
What to expect
For the upcoming meetup we are organizing, we have an exciting lineup of activities planned:
-Insightful presentations covering two practical applications of the Power Grid Model.
-An update on the latest advancements in Power Grid -Model technology during the first and second quarters of 2024.
-An interactive brainstorming session to discuss and propose new feature requests.
-An opportunity to connect with fellow Power Grid Model enthusiasts and users.
Your One-Stop Shop for Python Success: Top 10 US Python Development Providersakankshawande
Simplify your search for a reliable Python development partner! This list presents the top 10 trusted US providers offering comprehensive Python development services, ensuring your project's success from conception to completion.
HCL Notes and Domino License Cost Reduction in the World of DLAUpanagenda
Webinar Recording: https://www.panagenda.com/webinars/hcl-notes-and-domino-license-cost-reduction-in-the-world-of-dlau/
The introduction of DLAU and the CCB & CCX licensing model caused quite a stir in the HCL community. As a Notes and Domino customer, you may have faced challenges with unexpected user counts and license costs. You probably have questions on how this new licensing approach works and how to benefit from it. Most importantly, you likely have budget constraints and want to save money where possible. Don’t worry, we can help with all of this!
We’ll show you how to fix common misconfigurations that cause higher-than-expected user counts, and how to identify accounts which you can deactivate to save money. There are also frequent patterns that can cause unnecessary cost, like using a person document instead of a mail-in for shared mailboxes. We’ll provide examples and solutions for those as well. And naturally we’ll explain the new licensing model.
Join HCL Ambassador Marc Thomas in this webinar with a special guest appearance from Franz Walder. It will give you the tools and know-how to stay on top of what is going on with Domino licensing. You will be able lower your cost through an optimized configuration and keep it low going forward.
These topics will be covered
- Reducing license cost by finding and fixing misconfigurations and superfluous accounts
- How do CCB and CCX licenses really work?
- Understanding the DLAU tool and how to best utilize it
- Tips for common problem areas, like team mailboxes, functional/test users, etc
- Practical examples and best practices to implement right away
How information systems are built or acquired puts information, which is what they should be about, in a secondary place. Our language adapted accordingly, and we no longer talk about information systems but applications. Applications evolved in a way to break data into diverse fragments, tightly coupled with applications and expensive to integrate. The result is technical debt, which is re-paid by taking even bigger "loans", resulting in an ever-increasing technical debt. Software engineering and procurement practices work in sync with market forces to maintain this trend. This talk demonstrates how natural this situation is. The question is: can something be done to reverse the trend?
"Choosing proper type of scaling", Olena SyrotaFwdays
Imagine an IoT processing system that is already quite mature and production-ready and for which client coverage is growing and scaling and performance aspects are life and death questions. The system has Redis, MongoDB, and stream processing based on ksqldb. In this talk, firstly, we will analyze scaling approaches and then select the proper ones for our system.
Best 20 SEO Techniques To Improve Website Visibility In SERPPixlogix Infotech
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Best 20 SEO Techniques To Improve Website Visibility In SERP
The harps search_for_southern_exoplanets_01
1. Astronomy & Astrophysics manuscript no. main c ESO 2011
November 24, 2011
The HARPS search for southern extra-solar planets
XXXI. The M-dwarf sample
X. Bonfils1,2 , X. Delfosse1 , S. Udry2 , T. Forveille1 , M. Mayor2 , C. Perrier1 , F. Bouchy3,4 , M. Gillon5,2 , C. Lovis2 , F.
Pepe2 , D. Queloz2 , N. C. Santos6 , D. S´ gransan2 , and J.-L. Bertaux7
e
1
UJF-Grenoble 1 / CNRS-INSU, Institut de Plan´ tologie et d’Astrophysique de Grenoble (IPAG) UMR 5274, Grenoble, F-38041,
e
France
2
Observatoire de Gen` ve, 51 ch. des Maillettes, 1290 Sauverny, Switzerland
e
3
Institut d’Astrophysique de Paris, CNRS, Universit´ Pierre et Marie Curie, 98bis Bd Arago, 75014 Paris, France
e
4
Observatoire de Haute-Provence, CNRS/OAMP, 04870 Saint-Michel-lObservatoire, France
arXiv:1111.5019v2 [astro-ph.EP] 23 Nov 2011
5
Institut dAstrophysique et de G´ ophysique, Universit´ de Li` ge, All´ e du 6 Aoˆ t 17, Bat. B5C, 4000 Li` ge, Belgium
e e e e u e
6
Centro de Astrof´sica, Universidade do Porto, Rua das Estrelas, P4150-762 Porto, Portugal
ı
7
Service d’A´ ronomie du CNRS, BP 3, 91371 Verri` res-le-Buisson, France
e e
Received/Accepted
ABSTRACT
Context. Searching for planets around stars with different masses probes the outcome of planetary formation for different initial con-
ditions. The low-mass M dwarfs are also the most frequent stars in our Galaxy and potentially therefore, the most frequent planet
hosts.
Aims. This drives observations of a sample of 102 southern nearby M dwarfs, using a fraction of our guaranteed time on the
ESO/HARPS spectrograph. We observed 460 hours and gathered 1965 precise (∼ 1 − 3 m/s) radial velocities, spanning the pe-
riod from Feb. 11th, 2003 to Apr. 1st 2009.
Methods. This paper makes available the sample’s time series, presents their precision and variability. We apply systematic searches
for long-term trends, periodic signals and Keplerian orbits (from 1 to 4 planets). We analyze the subset of stars with detected signals
and apply several diagnostics to discriminate whether the observed Doppler shifts are caused by stellar surface inhomogeneities or
by the radial pull of orbiting planets. To prepare for the statistical view of our survey we also compute the limits on possible unseen
signals, and derive a first estimate of the frequency of planets orbiting M dwarfs.
Results. We recover the planetary signals corresponding to 9 planets already announced by our group (Gl 176 b, Gl 581 b, c, d & e,
Gl 674 b, Gl 433 b, Gl 667C b and Gl 667C c). We present radial velocities that confirm GJ 849 hosts a Jupiter-mass planet, plus
a long-term radial-velocity variation. We also present RVs that precise the planetary mass and period of Gl 832b. We detect long-
term RV changes for Gl 367, Gl 680 and Gl 880 betraying yet unknown long-period companions. We identify candidate signals in
the radial-velocity time series of 11 other M dwarfs. Spectral diagnostics and/or photometric observations demonstrate however that
they are most probably caused by stellar surface inhomogeneities. Finally, we find our survey sensitive to few Earth-mass planets for
periods up to several hundred days. We derive a first estimate of the occurrence of M-dwarf planets as a function of their minimum
mass and orbital period. In particular, we find that giant planets (m sin i = 100 − 1, 000 M⊕ ) have a low frequency (e.g. f 1% for
P = 1 − 10 d and f = 0.02+0.03 for P = 10 − 100 d), whereas super-Earths (m sin i = 1 − 10 M⊕ ) are likely very abundant ( f = 0.36+0.25
−0.01 −0.10
for P = 1 − 10 d and f = 0.35+0.45 for P = 10 − 100 d). We also obtained η⊕ = 0.41+0.54 , the frequency of habitable planets orbiting
−0.11 −0.13
M dwarfs (1 ≤ m sin i ≤ 10 M⊕ ). For the first time, η⊕ is a direct measure and not a number extrapolated from the statistic of more
massive and/or shorter-period planets.
Key words. Stars: late-type – planetary systems, technique: radial-velocity
1. Introduction Gatewood 1995), targeting M dwarfs has proven more success-
ful since.
M dwarfs are the dominant stellar population of our Galaxy (e.g.
Chabrier & Baraffe 2000). Compared to our Sun, they are cooler, At the forefront of planet discoveries, the radial-velocity
smaller and lower-mass stars. These characteristics ease the de- (RV) technique was first to unveil a candidate giant planet or-
tection of planets for many techniques and M dwarfs have there- biting an M dwarf. Three years after the discovery of 51Peg b
fore been included early in planet-search samples. While the first (Mayor & Queloz 1995), the detection of a giant planet orbiting
claimed detections (e.g. around Barnard’s star – van de Kamp the M dwarf GJ 876 (Delfosse et al. 1998; Marcy et al. 1998)
1963) were later found incorrect (Gatewood & Eichhorn 1973; proved that M dwarfs could form planets too. GJ 876 was actu-
ally one of a few tens of M stars monitored by radial-velocity
Send offprint requests to: X. Bonfils surveys, and its detection made the early impression that giant
e-mail: Xavier.Bonfils@obs.ujf-grenoble.fr planets could be common around late-type stars. Today, only
Based on observations made with the HARPS instrument on the 6 M dwarfs are known to host a planet with a minimum mass
ESO 3.6-m telescope at La Silla Observatory under programme ID > 0.5 MJup (see Table 1) and the view has progressively shifted
072.C-0488(E) toward a low rate of occurrence for giant planets, compared to
2. 2 X. Bonfils et al.: The HARPS M-dwarf sample
sun-like stars (Bonfils et al. 2006; Butler et al. 2004; Endl et al. 209458 b (Charbonneau et al. 2000; Mazeh et al. 2000; Henry
2006; Johnson et al. 2007; Cumming et al. 2008). et al. 2000).
Improvements of the RV technique has led to the discovery To complete the view of planetary-mass objects formed at
of lower-mass planets down to m sin i 1.9 M⊕ (Mayor et al. the lower end of the main sequence, let us mention the ∼ 5 MJup
2009). Below 25 M⊕ , there are 8 known M-dwarf hosts and they companion detected with RV measurements around the young
altogether host 12 such low-mass exoplanets. Hence, despite an brown dwarf Cha Hα 8 (Joergens & M¨ ller 2007) and the
u
adverse detection bias, planets of low-mass already appear more ∼ 5 MJup companion imaged around another young brown dwarf
frequent than giant planets (Bonfils et al. 2007). Among them, 2M1207 (Chauvin et al. 2004). The protoplanetary disks of both
GJ 581d and GJ 667Cc are noticeably interesting because they brown dwarfs were most likely not massive enough to form
have m sin i < 10 M⊕ and receive closely the amount of light such massive objects, since observations show that protoplan-
received by Earth in our Solar System (Udry & Santos 2007; etary disk masses scale at most linearly with the mass of the star.
Mayor et al. 2009, Delfosse et al., in prep.). Depending on their Both 2M1207b and Cha Hα 8b therefore probably formed like
atmosphere (thickness, albedo and chemistry) liquid water may stars rather than in protoplanetary disks.
flow on their surface – the standard criterium to define a habit- Table 1 lists the known M-dwarf hosts and their procession
able planet (Kasting et al. 1993; Selsis et al. 2007). of planets. For each planet, it gives the basic characteristics and
a reference to the discovery papers. In total, there are 35 planets
The transit technique has also been successful in detect-
in 28 planetary systems.
ing two planets transiting an M dwarf. One is GJ 436 b, a
Planets orbiting M dwarfs formed in a different environment
Neptune-mass planet initially detected with Doppler measure-
than those around solar-type stars, and therefore reflect a differ-
ments (Butler et al. 2006; Maness et al. 2007) and subsequently
ent outcome of the planetary formation mechanism. The mass
seen in transit (Gillon et al. 2007b). Finding that GJ 436 b un-
of the proto-planetary disk, its temperature and density profiles,
dergoes transits has enabled a wealth of detailed studies such
gravity, the gas-dissipation timescale, etc... all change with stel-
as the determinations of the planet’s true mass and radius and
lar mass (e.g. Ida & Lin 2005). For the construction of the Harps
measurements of its effective temperature and orbital eccentric-
spectrograph for ESO, our consortium has been granted 500 ob-
ity (Gillon et al. 2007a; Demory et al. 2007; Deming et al. 2007).
serving nights with the instrument spread over 6 years. We chose
Most recently, the Mearth project, a search for transiting plan-
to dedicate 10% of that guaranteed time to characterize the plan-
ets dedicated to late M dwarfs (Nutzman & Charbonneau 2008),
etary population for stars with masses < 0.6 M .
has unveiled a ∼ 6 M⊕ planet transiting the nearby M4.5 dwarf
This paper reports on our 6-year RV search for planets
GJ 1214 (Charbonneau et al. 2009). Like GJ 436b, it has a fa-
around M dwarfs and the outline is as follow. We first de-
vorable planetary to stellar radius ratio and is well suited to in-
scribe our sample (Sect. 2) and present the RV dataset collected
depth characterizations with current observatories. Both planets
(Sect. 3). We next perform a systematic analysis for variability,
are considered Rosetta stones to the physics of low-mass planets.
long-term trend and periodic signals (Sect. 4). We close that sec-
Anomalies in gravitational microlensing light curves can re- tion by an automated Keplerian multi-planet search. For all sig-
veal planetary systems kiloparsecs away from our Sun. Most fre- nals detected with enough confidence, we apply a suite of diag-
quently, the lenses are low-mass stars of masses 0.6 M and of nostics to disentangle Doppler shifts caused by bona fide planets
spectral types M and K. Up to now, the technique has found 12 from Doppler shifts caused by stellar surface inhomogeneities
planets in 11 planetary systems. Among those, 7 are giant planets (Sect. 5). Sect. 6 presents the detection limits for individual stars
and 5 fall in the domain of Neptunes and Super-Earths (Tab. 1). of our sample and Sect. 7 pools them together to estimate both
The technique is mostly sensitive to planets at a few AUs from the survey sensitivity and the frequency of planets orbiting M
their host which, for M dwarfs, is far beyond the stellar habit- dwarfs. Sect. 8 summarizes our results and presents our conclu-
able zone. The microlensing technique probes a mass-separation sions.
domain complementary to the RV and transit techniques and has
shown evidences that, at large separations, low-mass planets out-
number giant planets (Gould et al. 2006). 2. Sample
Ground-based astrometry applied to planet searches has been Our search for planets orbiting M dwarfs originates from RV ob-
cursed by false positives, of which Van de Kamp’s attempts servations started in 1995 with the 1.93m/Elodie spectrograph
around Barnards star are probably the most famous examples (CNRS/OHP, France). This former program aimed at determin-
(van de Kamp 1963; Gatewood & Eichhorn 1973). Fifty years ing the stellar multiplicity for very-low-mass stars (Delfosse
ago, Van de Kamp first claimed that a 1.6 MJup planet orbits et al. 1999) as well as the detection of their most massive plan-
Barnard’s star every 24 years. Over the following decades, he ets (Delfosse et al. 1998). In 1998, we started to run a similar
continued to argue for a planetary system around the star (van de program in the southern hemisphere, with the 1.52m/Feros spec-
Kamp 1982), despite growing evidence of systematics in the trograph (La Silla, Chile). With Feros’s early settings, we were
data (e.g. Gatewood & Eichhorn 1973; Hershey 1973). Radial- unsuccessful to improve on its nominal precision of ∼ 50 m/s.
velocity and astrometric data have now completely excluded Nevertheless, we benefitted from these observations to start with
the van de Kamp planets (Gatewood 1995; K¨ rster et al. 2003;
u a better sample on Harps, cleaned from spectroscopic binaries
Benedict et al. 2002), but Barnard’s star has been far from the and fast rotators for which precision radial-velocity is more dif-
only target with false astrometric detections. ficult.
Nevertheless, astrometry has proven useful to confirmed the Our Harps sample corresponds to a volume limited of M
planetary nature of a few radial-velocity detections, and to re- dwarfs closer than 11 pc, with a declination δ < +20o , brighter
move from the planet sample the low-mass stars seen with an than V = 14 mag and with a projected rotational velocity
unfavorable inclination (e.g. Halbwachs et al. 2000). Moreover, v sin i 6.5 km/s. We removed known spectroscopic binaries
thanks to HST/FGS astrometric observations, GJ 876b has been and visual pairs with separation < 5 (to avoid light contam-
the second exoplanet with a true mass determination (Benedict ination from the unwanted component). We have however en-
et al. 2002), soon after the detection of the transiting planet HD countered a few spectroscopic binaries and fast rotators which
3. X. Bonfils et al.: The HARPS M-dwarf sample 3
Table 1. Known exoplanets orbiting M dwarfs and their basic parameters
Radial-Velocity detections
Star Pl. m p sin i† i P a e ref. ref. in
[M⊕ ] [MJup ] [o ] [d] [AU] discovery‡ param.‡ sample
GJ 176 b 8.4 0.026 - 8.7(8) 0.07 0. (fixed) 25 25 y
GJ 317 b 380 1.2 - 69(2) 0.95 0.19 (006) 17 17 n
GJ 433 b 6.41 0.0202 - 7.36(5) 0.06 0. (fixed) 37 37 y
GJ 581 b 15.7 0.0492 > 40. 5.368(7) 0.04 0. (fixed) 8 23 y
c 5.4 0.017 > 40. 12.9(3) 0.07 0.17 (0.07) 13 23 y
d 7.1 0.022 > 40. 66.(8) 0.22 0.38 (0.09) 13,23 23 y
e 1.9 0.0060 > 40. 3.1(5) 0.03 0. (fixed) 23 23 y
GJ 649 b 106 0.333 - 59(8) 1.14 0.30 (0.08) 28 28 n
GJ 667C b 6.0 0.019 - 7.20(3) 0.05 0. (fixed) 37 37 y
c 3.9 0.012 - 28.1(5) 0.28 0. (fixed) 37 37 y
GJ 674 b 11 0.034 - 4.6(9) 0.04 0.20 (0.02) 12 12 y
GJ 676A b 1300 4.0 - 98(9) 1.61 0.29 (0.01) 36 36 n
GJ 832 b 200 0.64 - 3(416) 3.4 0.12 (0.11) 20 39 y
GJ 849 b 310 0.99 - 18(52) 2.35 0.04 (0.02) 11 39 y
GJ 876 b 839 2.64 48.(9) 61.0(7) 0.211 0.029 (0.001) 1,2 29 y
c 180 0.83 4(8) 30.2(6) 0.132 0.266 (0.003) 3 29 y
d 6.3 0.020 50 (fix.) 1.9378(5) 0.021 0.139 (0.032) 6 29 y
GJ 3634 b 6.6 0.021 - 2.645(6) 0.028 0.08 (0.09) 36 36 n
HIP 12961 b 110 0.35 - 57.4(3) 0.13 0.16 (0.03) 35 35 n
HIP 57050 b 40 0.3 - 41.(4) 0.16 0.3 (0.1) 34 34 n
HIP 79431 b 350 1.1 - 111.(7) 0.36 0.29 (0.02) 30 30 n
Transit detections
Star Pl. m†
p i P a e Rp ref. ref. in
[M⊕ ] [MJup ] [o ] [d] [AU] [R⊕ ] discovery‡ param.‡ sample
GJ 436 b 22.6 0.0711 85.(9) 2.643(9) 0.029 0.14 (0.01) 4.(2) 5,14 15, 16 n
GJ 1214 b 6.5 0.020 88.(6) 1.5803(9) 0.014(3) < 0.27 2.(7) 26 26 n
Microlensing detections
Star Pl. mp a M ref. ref.
[M⊕ ] [MJup ] [AU] [M ] discovery‡ param.‡
OGLE235-MOA53 b 830+250
−190 2.61+0.79
−0.60 4.3+2.5
−0.8 0.67±0.14 4 22
MOA-2007-BLG-192-L b 3.8+5.2
−1.8 0.012+0.016
−0.057 0.66+0.11
−0.06
+0.015
0.084−0.012 19 32
MOA-2007-BLG-400-L b 260+160
−99 0.83+0.49
−0.31 0.72+0.38 | 6.5+3.2 ††
−0.16 −1.2 0.30+0.19
−0.12 24 24
OGLE-2007-BLG-368-L b 20+7−8 0.06+0.02
−0.03 3.3+1.4
−0.8 0.641.4
−0.8 31 31
MOA-2008-BLG-310-L b 74±17 0.23± 0.05 1.25±0.10 0.67±0.14 27 27
OGLE-06-109L b 226±25 0.711±0.079 2.3±0.2 0.50±0.05 18 22
c 86±10 0.27±0.03 4.6±0.5 18 22
OGLE-05-169L b 13+4−5 0.041+0.013
−0.016 3.2+1.5
−1.0 0.49+0.14
−0.18 10 22
OGLE-05-390L b 5.5+5.5
−2.7 0.017+0.017
−0.008 2.6+1.5
−0.6 0.22+0.21
−0.11 9 124
††
OGLE-05-071L b 1200±100 3.8±0.4 2.1±0.1 | 3.6±0.2 0.46±0.04 7 21
MOA-2009-BLG-319-L b 50+44
−24 0.2±0.1 2.4+1.2
−1.6 0.38+0.34
−0.18 33 33
MOA-2009-BLG-387-L b 830+1300
−510 2.6+4.1
−1.6 1.8+0.9
−0.7 0.19+0.30
−0.12 38 38†††
†
The true mass (m p ) is reported for GJ 876 b, c, for the transiting planets GJ 436b and GJ 1214b and for all microlensing detections. The masses
o
given for GJ 876d assumes a 50 orbital inclination. We give minimum masses GJ581b, c, d and e, and dynamical consideration restrict coplanar
systems to i > 40o . Usually, uncertainties in planetary masses do not include the stellar mass uncertainty.
††
degenerated solution
†††
instead of 1σ uncertainties, we quote 90% confidence intervals from Batista et al. (2011)
‡
(1) Delfosse et al. (1998); (2) Marcy et al. (1998); (3) Marcy et al. (2001); (4) Bond et al. (2004); (5) Butler et al. (2004); (6) Rivera et al. (2005);
(7) Udalski et al. (2005); (8) Bonfils et al. (2005); (9) Beaulieu et al. (2006); (10) Gould et al. (2006); (11) Butler et al. (2006); (12) Bonfils et al.
(2007); (13) Udry & Santos (2007); (14) Gillon et al. (2007b); (15) Gillon et al. (2007a); (16) Demory et al. (2007); (17) Johnson et al. (2007);
(18) Gaudi et al. (2008); (19) Bennett et al. (2008); (20) Bailey et al. (2009); (21) Dong et al. (2009b); (22) Bennett (2009); (23) Mayor et al.
(2009); (24) Dong et al. (2009a); (25) Forveille et al. (2009); (26) Charbonneau et al. (2009); (27) Janczak et al. (2010); (28) Johnson et al. (2010);
(29) Correia et al. (2010); (30) Apps et al. (2010); (31) Sumi et al. (2010); (32) Kubas et al. (2010); (33) Miyake et al. (2010); (34) Haghighipour
et al. (2010) (35) Forveille et al. (2011); (36) Bonfils et al. (2011); (37) Delfosse (2011, in prep.); (38) Batista et al. (2011); (39) This paper.
were not known before our observations. We list them in Table 2 had their parallax revised since, now placing them beyond 11 pc
and discard them from the sample presented here. Note that (with π = 76.86 ± 3.97 and 88.3 ± 3.7 mas – Henry et al. 2006;
we also dismiss GJ 1001, Gl 452.1 and LHS 3836. The first two Smart et al. 2010). LHS 3836 was initially included based on its
stars were initially counted in our volume limited sample (with V magnitude in Gliese & Jahreiß (1991)’s catalog but our first
π = 103 and 96 mas, respectively – Gliese & Jahreiß 1991) and measurements were indicative of a much lower brightness.
4. 4 X. Bonfils et al.: The HARPS M-dwarf sample
Table 3 lists the 102 stars selected for the sample. Their co-
ordinates, proper motions and parallaxes are primarily retrieved 30
from the revised Hipparcos catalog (van Leeuwen 2007). A frac-
tion of the parallaxes, unavailable in the Hipparcos database,
were obtained from van Altena et al. (1995), Henry et al. (2006), 25
Reid et al. (1995) and the 4th Catalog of Nearby Stars (CNS4
– Jahreiss, priv. comm.). V-band magnitudes are taken from 20
Simbad and infrared J- and K-band magnitudes from 2MASS
(Cutri et al. 2003). We used the empirical Delfosse et al. (2000)’s
Number
mass-luminosity relationship together with parallaxes and K- 15
band photometry to compute the mass of each star. Infrared K-
band photometry and (J−K) colors are converted to luminosities 10
with Leggett et al. (2001)’s bolometric correction.
We also indicate in Table 3 the inner and outer limits for the
distance of the Habitable Zone using the recent-Venus and early- 5
Mars criterions, respectively, and Eq. (2) and (3) from Selsis
et al. (2007). The boundaries of the Habitable Zone are uncertain
0
and depend on the planet’s atmospheric composition. Extra-solar 6 8 10 12 14 16
planets found close to these edges have therefore to meet more V [mag.]
stringent conditions to be inhabitable. For more detailed consid-
erations, we refer the reader to more comprehensive models (e.g. 30
Selsis et al. 2007).
Our sample is composed of the closest neighbors to the Sun.
Nearby stars tend to have large proper motions and the projection 25
of their velocity vector may change over time, up to few m/s/yr
(Schlesinger 1917; K¨ rster et al. 2003). We therefore report the
u
20
value of their secular acceleration in Table 3.
To portray our sample, we show its V-mag. and mass dis-
Number
tributions in Fig. 1. For both distributions, the average (resp. 15
median) value is plotted with a vertical straight (resp. dashed)
line. The magnitudes and masses of planet hosts are also marked
with vertical ticks on top of the histograms. The target bright- 10
ness spans V=7.3 to 14 mag. with a mean (resp. median) value
of 11.25 mag. (resp. 11.43 mag.). The stellar mass ranges from 5
0.09 to 0.60 M with an average (resp. median) value of 0.30
M (resp. 0.27 M ). The smaller count seen in the 0.35-0.40 M
bin is unexplained but from statistical fluctuations. Interestingly, 0
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7
one can note that our sample covers a factor of ∼6 in stellar mass, Mass [M ]
while the mass step between our typical M dwarf (∼ 0.27 M )
and the typical Sun-like star (∼ 1 M ) corresponds to a factor Fig. 1. Sample distributions for V magnitudes and stellar
of less than 4. This means that planetary formation processes masses. The vertical dashed and plain lines locate the median
depending on stellar mass could lead to larger observable differ- and averaged values, respectively. The small ticks are explained
ences across our sample than between our M-dwarf sample and in Sect. 8.
Sun-like stars.
There are overlaps between our sample and others that sim-
ilarly targets M dwarfs to search for planets. Among them, we (instrument+telescope) greater than 6%. It is enclosed in a vac-
found published RV time-series for Gl 1, Gl 176, Gl 229, Gl 357, uum vessel, is pressure controlled to ±0.01 mbar and thermally
Gl 551, Gl 682, Gl 699, Gl 846 and Gl 849 in Endl et al. (2006, controlled to ±0.01 K. That ensures a minimum instrumental
hereafter E06), for Gl 1, Gl 229, Gl357, Gl 433, Gl 551, Gl 682, shift on the position of the spectrum image on the CCD or, prac-
Gl 699, Gl 846 and Gl 849 in Zechmeister et al. (2009, hereafter tically, a RV drift 0.5 m/s/night. To reference the origin of
Z09), and few others in detection papers, as for Gl 176 (Endl the instrumental RV drift, the fiber can be illuminated with a
et al. 2008), Gl 832 (Bailey et al. 2009) and Gl 849 (Butler et al. Thorium-Argon (ThAr) lamp at any time. Harps also offers a
2006). When possible, we compare our results to these time se- second fiber that can be illuminated with ThAr light simulta-
ries and, for completeness, additional comparison is given in neously while the scientific fiber receives star light. This mode
Appendix A. avoids the need to record frequent calibrations between scien-
tific exposures and can correct the small instrumental drift that
occurs while the stellar spectrum is recorded. Since the instru-
3. Observations mental drift during the night is small, this mode is only used
when a sub-m/s precision is required. Our observational strat-
To gather RV observations for the sample described above we egy for M dwarfs aims to achieve a precision of ∼ 1 m/s per
used the Harps instrument (Mayor et al. 2003; Pepe et al. exposure for the brightest targets. We chose therefore not to use
2004), a spectrograph fiber fed with the ESO/3.6-m telescope the second fiber and relied on a single calibration done before the
(La Silla, Chile). It covers the 3800−6800 Å wavelength do- beginning of the night. As the science and calibration spectral or-
main, has a resolution R ∼ 115 000 and an overall throughput ders are interlaced, avoiding the second fiber eludes light cross-
5. X. Bonfils et al.: The HARPS M-dwarf sample 5
Table 2. Spectroscopic binaries and fast rotators discarded a posteriori from the sample
Name α (2000) δ (2000) V [mag] Comment
L 225-57 02:34:21 −53:05:35 7.3 SB2
CD- 44-836B 02:45:14 −43:44:06 12.7 Fast Rotator / SB2
LHS 1610 03:52:42 +17:01:06 13.7 SB2
LHS 6167 09:15:36 −10:35:47 14.7 SB2 †
G 161-71 09:44:55 −12:20:53 13.8 Fast Rotator
GJ 1154A 12:14:17 +00:37:25 13.7 Unresolved SB2‡
LHS 3056 15:19:12 −12:45:06 12.8 SB
L 43-72 18:11:15 −78:59:17 12.5 Unresolved SB2‡
LTT 7434 18:45:57 −28:55:53 12.6 Unresolved SB2‡
Gl 867B 22:38:45 −20:36:47 11.4 Fast Rotator or unresolved SB2
†
previously detected by Montagnier et al. (2006)
‡ SB with variable spectral-line width
contamination between science and calibration spectra. This can
be a source of noise for the blue-most spectral orders, where we
only reach low signal-to-noise for M dwarfs. In particular, we 14
were interested in clean Ca ii H&K lines because they are a use-
ful diagnostic of stellar activity (see Sect. 5). 12
From the first light on Harps on February, 11th 2003 to the
end of our guaranteed time program on April, 1st 2009, we have 10
recorded 1965 spectra for the M-dwarf sample, for a total of
460 h of integration time. σ [m/s] 8
We computed RV by cross-correlating the spectra with a nu-
merical weighted mask following Baranne et al. (1996) and Pepe 6
et al. (2002). Our numerical mask was generated from the addi-
tion of several exposures taken on Gl 877, a bright M2 star of 4
our sample. Co-addition of spectra requires knowing their rela-
2
tive Doppler shifts. We computed RVs for Gl 877 spectra with
a first iteration of the template and re-built the template more 0
precisely. We obtained convergence just with a few iterations.
The numerical mask counts almost 10,000 lines and most of the 6 7 8 9 10 11 12 13 14 15
Doppler information in the spectrum. No binning is done. V [mag.]
The RV uncertainties were evaluated from the Doppler con-
Fig. 2. Internal (σi ) and external (σe ) errors as a function of
tent of individual spectra, using the linear approximation of a
V-band magnitudes, for stars with 6 or more measurements.
Doppler shift (Eq. 12 – Bouchy et al. 2001). This formula gives
more weight to spectral elements with higher derivative because
they are more sensitive to phase shifts and contribute more to comparison, Fig. 2 shows observed dispersions σe for all stars
the total Doppler content. It is important to note that we do not with more than 6 measurements (black squares, changed to tri-
sum the Doppler content of individual spectral elements over angles for clipped values). The σe are the observed weighted
the whole spectrum. The derivative of the spectrum has a higher r.m.s. and are related to the χ2 value :
variability against noise than the spectrum itself and, for low
signal-to-noise ratio, doing so would over-estimate the RV pre- (RV− < RV >)2 /σ2 χ2
cision. Instead, to mitigate the effect and compute more realis- σ2 =
e
i
= constant
. (1)
tic uncertainties, we applied the formula directly to the cross- 1/σ2
i 1/σ2 i
correlation profile, which has ∼ 30 times higher signal-to-noise
We discuss the difference between internal and external errors in
than the individual spectral lines (see appendix A in Boisse et al.
Section 4.
2010). To account for the imperfect guiding (∼30 cm/s) and
Our RV time series are given in the Solar System barycentric
wavelength calibration (∼50 cm/s) we quadratically added 60
reference frame and can be retrieved online from CDS. Prior to
cm/s to the Doppler uncertainty.
their analysis, the time series are corrected from the secular RV
As a trade-off between exposure time and precision we chose changes reported in Tab. 3. We also show the time series in Fig. 3
to fix the integration time to 900 s for all observations. We ob- (only available on-line), after subtraction of half the min+max
tained a precision1 σi ∼ 80 cm/s from Vmag = 7 − 10 stars and value for a better readability.
σi ∼ 2.5(10−V)/2 m/s for Vmag = 10 − 14. Our internal errors σi
(composed of photon noise + instrumental errors) are shown in
Fig. 2 where we report, for all stars with more than 6 measure- 4. Data analysis
ments, the mean σi (blue filled circle) as a function of the star’s
magnitude, with error bars corresponding to σi ’s dispersion. For Several planet-search programs have presented a statistical anal-
ysis for their survey (e.g. Murdoch et al. 1993; Walker et al.
1
As opposed to our precision, our measurement accuracy is poor. 1995; Cumming et al. 1999, 2008; Endl et al. 2002; Zechmeister
Absolute radial velocities given in this paper may not be accurate to ± et al. 2009). Often, statistical tests are applied to the time se-
1 km/s. ries in order to appraise the significance of trends or variability.
6. 6 X. Bonfils et al.: The HARPS M-dwarf sample
Then, the time series are searched for periodicities and, if a sig- data sets with χ2 virtual < χ slope gives us the false-alarm probabil-
2
nificant periodicity is found, the corresponding period is used as ity (FAP) for the slope model. For all stars, but the ones with 6
a starting point for a Keplerian fit. Again, statistical tests are ap- measurements or less, we generate 1,000 virtual time series. And
plied to decide whether a sinusoidal or a Keplerian model is a because that method probes FAPs greater than O(1/N!) only, we
good description for the time series. In this section, we follow limit the number of trials to N! for stars with fewer measure-
the same strategy and add a heuristic method based on genetic ments.
algorithms to the systematic search for Keplerian signals. Table 4 gives the slope coefficient α as well as P(F) and
FAP values for all time series. The P(F) and the FAP values
4.1. Excess variability are reported in boldface when below a threshold of 1%, to point
high confidence level in the slope model.
Once we have computed the RVs, the Doppler uncertainties (σi ) Among our sample and according to the FAP values, we
and the RV dispersion (σe ) for each star, the first step is to test find that 15 stars have time series better described by a slope
our time series for variability. In Fig. 2, we have reported both σi than a simple constant. They are Gl 1, LP 771-95A, Gl 205,
and σe as a function of stellar magnitudes for all stars with more Gl 341, Gl 382, Gl413.1, Gl 618A, Gl 667C, Gl 680, Gl 699,
than 6 measurements. Apart from one star (Gl 447, which has 6 Gl 701, Gl 752A, Gl 832, Gl 849 and Gl 880. We also see that,
RVs only), we have σe σi . The σe have a lower envelope that while LP 771-95A, Gl 367, Gl618A, Gl 680 and Gl 880 displays
matches the σi ’s envelope for Vmag = 10 − 14 and that is slightly smooth RV drifts, the other 10 stars seems to obey a more com-
above (∼ 2 m/s) in the brighter range Vmag = 7 − 10. plex variability. According to P(F) values, we find that the same
To test whether the observed RVs vary in excess of our inter- 15 stars plus 8 more have a significant chi squared improvements
nal errors, we first compare the expected variance < σ2 > (the
i
when we fit a slope. They are Gl54.1, Gl 250B, Gl 273, Gl 367,
mean internal error) to the measured variance σ2 by applying a Gl 433, Gl 551, Gl 674 and Gl 887.
e
σ2
F-test, which gives a probability P(F) to the F-value F = <σie>2
(e.g. Zechmeister et al. 2009). As another test for variability, we 4.3. Periodicity
also compute the χ2 2
constant for the constant model and P(χconstant ),
the probability of having χconstant given the σi . For both the F-
2 In our search for planets, variability selects the stars to focus
test and the χ2 -test, a low probability means that photon noise, on and trends reveal yet uncompleted orbits. Our next step in
calibration uncertainty and guiding errors are not sufficient to ex- the search for planetary candidates is to look for periodic sig-
plain the observed variability. In such a case, one has to invoke nals. The classical diagnostic for periodic coherent signals in
an additional source for variability, from unaccounted noise to unevenly spaced time series is the Lomb-Scargle periodogram
planetary companions. (Lomb 1976; Scargle 1982) or, to account for the unknown sys-
We report σi , σe , P(F), χ2 and P(χ2 ) in Table 4 and change tem’s mean velocity, its generalized version, the floating-mean
the P(F) and the P(χ2 ) values to boldface when smaller than periodogram (Cumming et al. 1999).
1%, i.e. when they indicate a confidence level for variability We therefore compute generalized Lomb-Scargle peri-
higher than 99%. Using this criterion, the F probabilities (resp. odograms for all our time series with at least 6 measurements.
the χ2 probabilities) indicate that 45% (resp. 63%) of our sam- We follow the formalism developed in Zechmeister & K¨ rster u
ple displays an excess variability. When focusing on stars with (2009), and choose a power normalization where 1.0 means that
Vmag = 7 − 10, all stars but two are found more variable than a sinusoidal fit is perfect (χ2 = 0) and where 0.0 means that a
expected according to P(F), and all stars according to P(χ2 ). sinusoidal fit does not improve χ2 over a constant model. We cal-
The reason is that our external error never reaches the ∼70 cm/s culate false-alarm probabilities very similarly to our trend anal-
threshold estimated for the brighter range of our sample (but ysis, with a bootstrap randomization (preferred to a F-test). We
rather 1.5−2 m/s), and is dominated by photon noise for a third create 1,000 virtual time series by shuffling the original data set.
of the sample in the Vmag = 10 − 14 range. For each individual data set we compute a periodogram and lo-
cate the highest power. Considering all periodograms from all
virtual data sets, we compute the distribution of the power max-
4.2. Trends ima. The power value that is above 99% of all trial powers is then
considered as the 1% FAP. More generally, we attribute a FAP
Next, we examine the time series for possible trends. They may to the maximum power value found in the original data set by
correspond to incomplete orbits and betray the presence of long- counting the fraction of the simulated power maxima that have a
period companions. For each star, we adjust a slope α (RV = larger value.
αt + β) to the RV data and evaluate the χ2 value of that model.
slope We show all periodograms in Fig. 16 (only available in elec-
To know whether the slope is a better description to the data tronic format). The periods corresponding to the highest power,
than the no slope model, we use two statistical tests. First, we use the corresponding signal semi-amplitude, the χ2 , as well as the
the F-test to gauge whether a lower χ2 compared to χ2
slope constant is associated FAPs are reported in Table 5. As previously, we
a sufficient improvement to justify an additional free parameter boldface the significant signal detections, i.e. the periods with
(2 for the slope model against 1 for the constant model). a power excess that has a FAP < 1%.
Also, because the F-test statistics is ill-behaved for non nor- In ideal cases, long-term variability only affects the long-
mally distributed uncertainties, we use a less-sensitive test based period range of the periodogram. However, the sparse sampling
on bootstrap randomization. That time, we generate virtual RV of our time series can cause power excess from a long-period
time series by shuffling the original data, i.e., we keep the same signal to leak to shorter periods. Removing the long-term signif-
observing dates and attribute to each date a measurement ran- icant trends cleans the periodogram and may reveal periodic sig-
domly chosen among the other dates, without repeating twice nal at shorter periods. Thus, we also compute the periodogram
a given measurement. On each virtual time series, we adjust a for the time series after removing the slope adjusted in the pre-
slope and compute its χ2 virtual value. Then, the fraction of virtual vious section, as well as corresponding false-alarm probabilities
7. X. Bonfils et al.: The HARPS M-dwarf sample 7
(FAP2 in Table 5). We record a noticeable change for Gl 618A require at least 12 RVs per planet in the model. Hence we use a
and Gl 680 only. No power excess remains in their periodograms 1-planet model for 12 RVs, both a 1-planet and a 2-planet model
after subtraction of the slope, meaning their RV variation are for stars with more than 24 RVs, and 4 different models (1−4
mostly linear drifts. planets) for stars with more than 48 RVs. To complement those
Our periodicity analysis identifies 14 stars with power excess models we also use the same suite of models with the addition of
with FAP2 < 1% are : Gl 176, G 205, Gl 273, Gl 358, Gl 388, a linear drift. We allow Yorbit to run for 150 seconds per planet
Gl 433, Gl 479, Gl 581, Gl 667C, Gl 674, Gl 832, Gl 846, Gl 849 in the model.
and Gl 876. The star Gl 887 additionally has FAP approaching Just as for the periodicity analysis, evaluating the credence of
our 1% threshold. the model is essential. The χ2 of solutions necessarily improves
After identifying possible periodicities, we use the candi- for more complex models as the number of degree of freedom
date periods as starting values for Keplerian fits. We search the increases, and we want to evaluate whether this improvement is
residuals for periodic signals again, computing periodograms statistically significant or occurs by chance. As previously, we
(see Fig. 17 in the online material) and locating power excesses generate virtual datasets by shuffling the original data and re-
with FAP < 1%. We find a probable second periodic signal for taining the dates. We create 1,000 virtual datasets and refit all
Gl 176, Gl 205, Gl 581, Gl 674 and Gl 876 (Table 6). We notice tested models 1,000 times with Yorbit. For each star and model,
that Gl 667C, Gl 832 and Gl 846 have FAP approaching our 1% we obtain 1,000 χ2 values and count how many are below the χ2
threshold. Although not shown here, a third iteration only reveals measured on the original data. This gives the FAP for that model,
coherent signals for Gl 581 and, possibly, Gl667C. A fourth iter- compared to the no-planet hypothesis. A model is considered to
ation found signal for Gl 581 only. improve χ2 significantly when less than 1% of the virtual trials
give as low a χ2 .
4.4. Keplerian analysis
Once we find a significant model, more complex models are
then evaluated against that model, and not against simpler mod-
Even in its generalized form, the Lomb-Scargle periodogram is els anymore. We consider signals in that model are detected (i.e.,
optimal for sinusoidal signals only. Eccentric orbits spread the for instance, we assume the system is composed of 2 planets if
spectral power on harmonics, decreasing the power measured at that model is a 2-planet model). To generate the virtual datasets
the fundamental period, and fitting a Keplerian function is an ob- we use the residuals around the best solution for the new ref-
vious improvement. Compared to a periodogram search, it can erence model (i.e., in our example, the residuals around the 2-
detect planets with high eccentricity against a higher noise. It planet model). Shuffling the residuals (and retaining the dates),
is often not used because it is non-linear in some of the orbital we again create 1,000 virtual datasets and fit the more complex
parameters. Traditional non-linear minimizations can only con- models using Yorbit. How many χ2 from these virtual trials are
verge to a solution close to a starting guess, possibly far from the lower than the best χ2 obtained on the actual RVs then gives the
global optimum. Applying non-linear minimization from many FAP for the complex models, compared to the simpler model.
starting guesses becomes quickly impracticable when the num- We report the parameters of the best solutions for each star
ber of planets increases. Keplerian functions are indeed transcen- and model in Table 7. In Tables 8 and 9, we report the FAP of the
dent and evaluating the radial velocity at a given time therefore models, compared to selected simpler models. In both tables, we
need an integration which is computationally expensive. Finally, boldface the models with FAP<1%. Of the 43 stars with more
the sequential approach outlined above requires a higher signal- than 12 measurements, 19 have RVs well modeled by 1 or more
to-noise for systems with several planets on commensurable or- planets. Among them, we recover all stars with probable RV pe-
bits (i.e. with RV pulls of similar amplitudes). riodicity except Gl 680 that has less than 12 measurements and
To work around these shortcomings, we make use of a hybrid was not tested. In the following section, we discuss the interpre-
method based on both on a fast non-linear algorithm (Levenberg- tation of these candidate signals.
Marquardt) and genetic operators (breeding, mutations, cross-
over). The algorithm has been integrated by one of us (D.S.)
in an orbit analysis software named Yorbit. We give a brief 5. Interpretation
overview of this software here, but defer its detail description
to a future paper (S´ gransan et al. in prep.). While a popula-
e The above analysis reveal Keplerian signals in our time series,
tion of typically 1, 000 solutions evolves, the top layer of Yorbit but Doppler shifts do not always correspond to planets. To vet
evaluates the performances of the different minimization meth- a RV variability against stellar activity, we make use of several
ods and tunes their time allocation in real time. Genetic algo- diagnostics. The shape of the cross-correlation function (CCF)
rithms efficiently explore the parameter space on large scales. in particular is often informative. While its barycenter measures
They thus score well and are given more CPU time during the the radial-velocity, its bisector inverse slope (BIS – Queloz et al.
early phase of the minimization. Once promising solutions are 2001) and its full width half maximum (FWHM) can diagnose
found, non-linear methods converge much more efficiently to- inhomogeneities of the stellar surface. Alternatively, spectral in-
ward the local optima. Hence, when new solutions arise outside dices built on Ca ii H&K or Hα lines can also diagnose inhomo-
of local minima, the non-linear methods are given more CPU geneities in the stellar chromosphere and photosphere, respec-
time. This heuristic approach has proved very efficient and the tively (Bonfils et al. 2007). Finally, we obtained photometric ob-
solution to multi-planet systems is found in few minutes only, servations of a few stars to check whether plages or spots could
on common desktop computers. produce the observed Doppler changes.
We search for planets using Yorbit on all stars with more
than 12 measurements, neglecting planet-planet interactions at 5.1. Planetary systems
this point. We scaled the complexity of the tested models with
the number of measurements. Although in principle 5N+1 RVs Among the stars with clear periodic/Keplerian signals, we of
are enough to obtain a Keplerian fit to an N-planet system, we course recover several planets that were previously known. In
wish to minimize the number of spurious solutions and arbitrary total, 14 planets are known to orbit 8 M dwarfs of our sample.
8. 8 X. Bonfils et al.: The HARPS M-dwarf sample
Nine were found by this program (Gl 176 b, Gl 433 b, Gl 581 b, between Gl581 c and d. However, we most recently demonstrate
c, d &e, Gl 667C b and Gl 674 b), one more was found in 1998 those planets do not exist (Forveille et al., submitted).
by our former program on ELODIE (Gl 876 b), 2 were detected
by concurrent programs and already confirmed by this program
(Gl 876 c & d) and 2 were detected by concurrent programs and • Gl 667C : This is a M2V dwarf we have intensively ob-
confirmed in this paper (Gl 832 b and Gl 849 b). served. We find several coherent signals in RV data and pos-
sibly identify the rotation period on FWHM measurements of
the cross-correlation function. Fitting a 1-planet model plus a
• Gl 176 : From HET radial-velocity data, it was proposed ∼ 1.8 m s−1 yr−1 linear drift to account for the A+B stellar-binary
that it hosts a m sin i = 24 M⊕ planet in 10.2-d orbit (Endl companion to Gl 667C, converges toward a minimum mass of a
et al. 2008). However, we found our HARPS data incompat- super-Earth (m sin i = 5.9M⊕ ) on a short-period orbit (7.2 day).
ible with that planet (Forveille et al. 2009). Instead, we have Adding one more planet to the model makes the fit converge to-
shown evidence for a lower-mass planet with a shorter period ward a ∼ 180 day period and a very eccentric solution, while
(m sin i = 8 M⊕ ; P = 8 d). Much like Gl 674 (see below), Gl 176 the power excess identified in the periodogram of the first model
is a moderately active M dwarf. We also observe a second pe- residuals is located around 90 day. Finer analysis actually inter-
riodic signal (P ∼ 40 d), that has marginally higher power than prets that second signal as a possible harmonic of a (half-)yearly
the 8-d signal in our periodogram. Thanks to photometric ob- systematic affecting few data points (Delfosse et al., in prep.).
servations and to spectroscopic indices measured on the same Filtering the signals of 2 planets plus a linear drift reveals an-
spectra, we identified the 40-d signal as due to a spot rather than other candidate planet (P3 = 28 d; m sin i = 3.4 M⊕ ). This can-
a second planet (Forveille et al. 2009, see). We note that our sys- didate receives about 90% the amount of light received by Earth
tematic Keplerian search for planets converges to solutions with in our Solar System and we speculate the planet is a habitable
different periods and very high eccentricities. This is mostly be- canidate (see Delfosse et al., in prep., for a detailed description).
cause the signal associated with the 40-d period might be poorly
described by a Keplerian function with a large eccentricity. The
method converges to the same periods as the periodogram anal- • Gl 674 : Only 4.5 pc away from our Sun, this M2.5 dwarfs
ysis when we restrict the range of eccentricities to < 0.6. hosts at least one low-mass planet (m sin i = 11 M⊕ ; P = 4.7 d –
Bonfils et al. 2007). Although a second periodic signal exists for
Gl 674 (P2 ∼ 35 d), analysis of spectroscopic indices and photo-
• Gl 433 : This nearby M2V dwarf is rather massive (M = metric observations shows that this additional signal originated
0.48 M ) for our sample. The periodogram of our HARPS RVs from stellar surface inhomogeneities. Today and with additional
shows a clear power excess at a 7.2-d period. We failed to find a measurements, subtracting the 4.7-d periodic signal and com-
counter part to that signal in our activity indicators. Also, based puting a periodogram of the residuals shows power excess at a
on the intensity rather than the variability of Hα and Ca ii lines, period of ∼ 25 d instead of 35. If due to a planet, it would corre-
the star seems to have a weak magnetic activity, and most prob- spond to a super-Earth in Gl 674’s habitable zone. However, the
ably a low rotational velocity. It is therefore likely that a planet semi-amplitude K of the Keplerian orbit of that second planet
revolves around Gl 433 every 7.2 days. A χ2 minimization of is ∼ 3.8 m/s, significantly above the residuals around the 2007
Harps RVs lead to a minimum mass of m sin i = 6 M⊕ for that combined fit (r.m.s.∼80 cm/s). There are two different interpre-
planet. We note that Zechmeister et al. (2009) have reported tations for this apparent inconsistency : either the 2007’s solu-
UVES radial velocities for Gl 433 and found no significant pe- tion excludes the present solution and today’s 25-d periodicity
riodicity. The semi-amplitude of our solution 3.5±0.4 m/s trans- is spurious or, the 2007’s fit absorbed both the 35- and the 25-d
lates to an r.m.s. of 5.0±0.6 m/s that is nonetheless compatible signals, simultaneously.
with the 4.4 m/s r.m.s. reported in Z09. Also, we found Z09’s The Keplerian analysis presented in Sect. 4.4 find a lower
RVs compatible with our data, provided that we use a model significance of only ∼ 94.6% for the second signal. We nev-
composed of a Keplerian plus a low order polynomial to fit the ertheless apply further diagnostics. Restricting the data set to
merged data sets. We refer the reader to Delfosse et al. (in prep.) the 2007’ RVs, we try a 1 planet+sine wave model instead of 2
for a detailed description. Keplerians and found almost equally low residuals (r.m.s ∼ 1.1
m/s). That strongly opposes the presence of an additional planet
with a 3.8 m/s semi-amplitude with short or moderate orbital pe-
• Gl 581 : That system counts at least four planets, which we riod. On the other hand, periodograms of the Hα and Ca ii H+K
reported in three papers : Bonfils et al. (2005); Udry & Santos indexes continue to peak at a ∼ 35-d period (Fig. 4), indicating
(2007); Mayor et al. (2009). We also performed a stability anal- that the signal remains coherent for these indicators. A decorre-
ysis for the system in Beust et al. (2008), updated in Mayor et al. lation between spectral indexes and RVs is then hard to explain.
(2009). Composed of one Neptune-mass planet and three super- We conclude that the case for an additional planet is not strong
Earths, the system is remarkable because it includes both the first enough with the present data set, and that data gathered after
possibly habitable exoplanets (Gl 581c &d – Selsis et al. 2007; Apr. 1st 2009, will be necessary to conclude.
von Bloh et al. 2007) and the lowest-mass planet known to date
(Gl 581e - m sin i = 1.9 M⊕ ). Besides, we found that stability
constrains its configurations. In the coplanar cases, inclinations • Gl 832 : A decade long RV campaign with the Anglo
lower than ∼ 40o induce too strong interactions between “b” Australian Telescope (AAT) has revealed that Gl 832 hosts a
and “e”, and “e” is ejected in a few hundred thousands years. long-period companion with a period almost as long as that sur-
A lower bound on the inclinations translates to upper bounds vey (∼ 9.5 yr – Bailey et al. 2009). The best fit to AAT data lead
for planetary masses. Gl 581e, for instance, would not be more to a minimum mass m sin i = 0.64 MJup . Our HARPS data do not
massive than ∼ 3 M⊕ if the system is coplanar. In 2010, Vogt span as much time and, while they do confirm with a high con-
et al. have proposed that 2 more planets orbit Gl 581, one having fidence level the long-period RV variation, they can not confirm
m sin i = 3.1 M⊕ and being in the middle of the habitable zone, the planetary nature of Gl 832b by themselves. Together with
9. X. Bonfils et al.: The HARPS M-dwarf sample 9
. .
0.6
Gl849 gtokeck
0.5
0.4
Power
0.3 40
0.2
0.1 20
RV [m/s]
0.0
0.6 0
0.5
0.4 −20
Power
0.3
0.2 −40
0.1
20
0.0 0
O−C [m/s]
10 101 102 103 104 10
Period [day] 0
−10
−20
Fig. 4. Periodograms of Ca II H+K (Top) and Hα (Bottom) in-
1500 2000 2500 3000 3500 4000 4500
dexes for Gl 674.
. JD − 2450000.0 [days] .
. .
Gl832 gtoaat Fig. 6. Best solution for the model 1 planet+drift, with Keck
20 (blue) and HARPS (red) RV for Gl 849.
10
part in our activity indicators (based on the shape of the cross-
RV [m/s]
correlation function or Hα and Ca ii spectral indices). Our obser-
0 vations confirm that Gl 849 hosts a Jupiter-mass companion.
Fitting a Keplerian orbit to HARPS observations alone con-
−10
verges toward a minimum mass of m sin i = 1.17 ± 0.06 MJup
and a period P = 2165 ± 132 d. Together with the Keck RVs
however, one planet is not sufficient to explain all the RV mo-
−20 tion. As already suspected from Keck data, a long-term change
20 is superimposed on the first periodic signal. We therefore fit
the merged data set with a 1 planet+drift, a 2 planets and a 2
O−C [m/s]
10
0 planets+drift model and calculate their respective FAPs. We find
−10 that a model more complex than 1 planet+a drift is not justified.
−20 For that model, our best solution ( χ2 = 1.96) corresponds to a
r
1000 1500 2000 2500 3000 3500 4000 4500 Jupiter-mass planet (m sin i = 0.99 ± 0.02 MJup ; P = 1852 ± 19 d;
JD − 2450000.0 [days] e = 0.04 ± 0.02) plus, a RV drift with a slope of −3.84 m/s/yr
. .
(Fig. 6; Tab. 10). Because Gl 849 is a nearby star (d= 8.77 ± 0.16
Fig. 5. Best solution for the model 1 planet, with AAT (blue) pc), the long-period massive companion makes it an excellent
and HARPS (red) RV for Gl 832. target for astrometric observations and direct imaging with high
angular resolution.
the AAT data2 , our HARPS RVs refine the orbit of Gl 832b. A • Gl 876 : That system was known to harbor planets before our
Keplerian fit using Yorbit converges to m sin i = 0.62±0.05 MJup observations started and at that time, was even the only plan-
and P = 3507 ± 181 d (Fig. 5). Our Keplerian analysis (§ 4.4) etary system centered on an M dwarf. The first giant planet
finds a possible second signal with a 35-d period. That second found to orbit GJ 876 was detected simultaneously by members
signal however, does not reach a 99% significance level in either of our team using the ELODIE and CORALIE spectrographs
our periodicity nor our Keplerian analysis. Some power excess is (Delfosse et al. 1998) and by the HIRES/Keck search for exo-
seen around ∼40 d in the BIS periodogram, uncomfortably close planets (Marcy et al. 1998). The system was later found to host
to the possible 35-d periodicity. We keep measuring Gl 832 to a second giant planet in a 2:1 resonance with GJ 876b (Marcy
clarify whether a second periodic signal is present and assess its et al. 2001). The third planet detected around GJ 876 was the
true nature. first known super-Earth, Gl 876d (Rivera et al. 2005). Because
the 2:1 configuration of the two giant planets leads to strong
• Gl 849 : This M3V dwarf is known since 2006 to host a interactions, the orbits differ significantly from Keplerian mo-
Jupiter-mass companion (Butler et al. 2006). The RV variation tions. To model the radial velocities, one has to integrate the
is clearly seen in our HARPS observations, and has no counter planet movement with a N-body code. This lifts the sin i de-
generacy and measures the masses of the giant planets. A full
One RV point (with Julian Date = 2 453 243.0503) has different
2 N-body analysis was first performed for GJ 876 by Laughlin &
values in Table 1. and Fig. 2 of Bailey et al. (2009). Bailey and collab- Chambers (2001) and Rivera & Lissauer (2001). From an up-
orators kindly informed us of the correct value (−2.1 ± 2.5 m/s) dated set of Keck RVs, Rivera et al. (2005) found the third planet
10. 10 X. Bonfils et al.: The HARPS M-dwarf sample
Table 10. Fitted orbital solutions for the Gl 849 (1planet + a linear drift) and Gl 832 (1 planet).
Parameter GJ 849 b GJ 832 b
P [days] 1845 ± 15 3507 ± 181
T [JD-2400000] 54000 ± 150 54224 ± 302
e 0.05 ± 0.03 0.08 ± 0.05
ω [deg] 298 ± 29 254 ± 35
K [m s−1 ] 24.4 ± 0.7 14.1 ± 1.1
V(Keck/AAT ) [km s−1 ] −0.0192 ± 0.0012 0.0033 ± 0.0013
V(Harps) [km s−1 ] −15.0896 ± 0.0005 13.3471 ± 0.0013
Slope [m s−1 yr−1 ] −4.76±0.33 -
f (m) [10−9 M ] 2.77 1.00
m2 sin i [M⊕ ] 0.91 0.62
a [AU] 2.32 3.46
σ (O-C) (AAT/Keck) [ms−1 ] 3.64 4.70
σ (O-C) (Harps) [ms−1 ] 2.08 1.77
χ2
red 1.83 2.36
only because planet-planet interactions were properly accounted 0.40
0.35
in the fitting procedure. Those authors still had to assume copla- 0.30 Ca II H+K
nar orbits to assign a mass to each planet. Bean et al. (2009) then (all data)
Power
0.25
combined the Keck RVs with HST astrometry to both measure 0.20
the masses in the coplanar case and to measure the relative incli- 0.15
0.10
nation between planets “b” and “c”. Most recently, we used our 0.05
HARPS data and the published Keck measurements to model the 0.00
system and measure the relative inclination of both giant planets 0.35
(< 1o ), relying on RVs only. The paper (Correia et al. 2010) also 0.30 Hα
(all data)
analyzed the dynamical stability and show that the librations am- 0.25
Power
plitude are smaller than 2o thanks to a damping process acting 0.20
0.15
during the planet formation.
0.10
0.05
5.2. Activity dominated variations 0.00
0.45
0.40
We group in this section the “active” cases. They are stars tested Ca II H+K
0.35 (2,453,600<BJD<2,453,900)
positively for periodicity and/or Keplerian signal, and their mea- 0.30
Power
surement variability correlates with an activity indicator. We do 0.25
0.20
not show all diagnostics for each star, but rather pick the most 0.15
illustrative. A statistical discussion of all activity indicators will 0.10
0.05
be presented in a separate paper (Bonfils et al. 2010, in prep.). 0.00
0.5
• Gl 205 : A periodogram of the velocities identifies excess 0.4 Hα
(2,453,600<BJD<2,453,900)
Power
power around 32.8 d. Our Keplerian search with Yorbit, for a 0.3
single planet or for a 1 planet+drift model, converges toward 0.2
either a similar period or 0.970 d, an alias with the 1-d sam-
0.1
pling. We find indications that the variation is intrinsic to the
star from both spectral indices and photometric observations. 0.0 0
10 101 102 103 104
Considering the whole dataset, we identify excess power around Period [day]
33 d in periodograms of Hα and Ca ii H+K indices, though,
those peaks are not the highest. Restricting instead the dataset
to one observational season, a strong power excess around the Fig. 7. For Gl 205, the top 2 panels show the periodograms for
period 33 d dominates the periodogram (Fig. 7). With addition- Ca II H+K index and Hα index, including all data. The bot-
ally note a high correlation between Hα and Ca ii H+K indices tom 2 panels show the periodograms for Ca II H+K index and
(their Pearson correlation coefficient is 0.97), suggesting both Hα index, restricting the dataset to one observational season
variations originate from the same surface homogeneity. Also, (2, 453, 600 < BJD < 2, 543, 900).
photometric monitoring of Gl 205 reports a similar period for the
stellar rotation (33.61 d – Kiraga & Stepien 2007). The observed
RV modulation is most probably due to surface inhomogeneities, the first harmonic of that period (∼ 13 d). The RV modulation
which remains stable over one season but not over several. is well described by a Keplerian orbit. However, we also ob-
serve similar variability in the FWHM of the CCF as well as a
possible anti-correlation between RV and spectral lines asymme-
• Gl 358 : We have gathered 28 measurements for Gl 358. They try (see Fig 8), as measured by the CCF bisector span (Queloz
show significant variability with a periodicity of ∼ 26 d. In the et al. 2001). The Pearson’s correlation for BIS and RV is −0.40,
RV time series periodogram, we also identify power excess at and rises to −0.67 for the 2007 measurement subset. Photometric
11. X. Bonfils et al.: The HARPS M-dwarf sample 11
0.7 0.7
0.6 0.6
0.5 0.5
Power
Power
0.4 0.4
0.3 0.3
0.2 0.2
0.1 0.1
0.0 0 0.0 0
10 101 102 103 104 10 101 102
Period [day] Period [day]
−8 −5
−10 −10
−12
BIS [m/s]
BIS [m/s]
−15
−14
−20
−16
−25
−18
−20 −30
−22 −35
−20 −15 −10 −5 0 5 10 15 20 −40 −30 −20 −10 0 10 20 30 40 50
RV− <RV> [m/s] RV− <RV> [m/s]
Fig. 8. Top : Periodogram for the FWHM of CCFs for Gl 358. Fig. 9. Top : Periodogram for the CCFs bisector span for Gl 388.
Bottom : Possible correlation between bisector spans and RV Bottom : Strong correlation between bisector spans and RV data
data for Gl 358. for Gl 388.
0.7
monitoring by Kiraga & Stepien (2007) found a rotational period 0.6
of 25.26 d for Gl 358. All this favors a scenario where a stellar 0.5
Power
surface inhomogeneity such as a spot or a plage produces the RV 0.4
0.3
change, rather than a planet.
0.2
0.1
• Gl 388 (AD Leo) : The periodogram of its RV time series 0.0 0
10 101 102
shows an important power excess at short-period, with two Period [day]
prominent peaks at 1.8 and 2.22 d, consistent with 2.24-d ro-
tational period reported by Morin et al. (2008). These are 1- 1.03
d aliases of each other, and the later is slightly stronger. Here, 1.02
the bisector span demonstrates that stellar activity is responsible
for the variation. Its periodogram shows a broad power excess 1.01
Flux
at short period, and it is strongly anti-correlated to RV (with a 1.00
Person’s correlation coefficient of −0.81 – see Fig. 9). Correcting 0.99
from the BIS-RV correlation by subtracting a linear fit does de- 0.98
crease the r.m.s from 24 to 14 m/s, but leaves some power excess
0.97
around ∼ 2 d. 0.0 0.2 0.4 0.6 0.8 1.0
Phase
• Gl 479 We observe significant power excesses in the RV time Fig. 10. Top : Periodogram of Gl 479 photometry. Bottom :
series at two periods, ∼11.3 and 23 − 24 d, with the shorter pe- Phase-folded to the 23.75-d period.
riod roughly half the longer one. The RVs vary with an ampli-
tude of ∼27 m/s and an r.m.s. of 4.13 m/s. Modeling that RV
variability with Keplerians converges toward 2 planets with very very slow rotation. We cannot correlate the photometry with RV
similar periods (23.23 and 23.40 d), which would clearly be an variation because they were not taken at the same time but, phas-
unstable system. Gl 479 shares its M3 spectral type with Gl 674 ing both to a 23 d period, we found a 0.24-phase shift consistent
and Gl581, which we use as benchmarks for their moderate and with a spot. The observed RV variability is therefore probably
weak magnetic activity, respectively. From a spectral index built due to Gl 479 magnetic activity rather than to planets.
on the Ca ii H&K lines, we find that Gl 479 has a magnetic ac-
tivity intermediate to Gl 674 and Gl 581. Neither the bisector nor
the spectral indices show any significant periodicity or correla- • Gl 526 We observe RV periodicity with power excess close
tion with RVs. However, we have complemented our diagnos- to 50 d and a FAP approaching 1%. As expected for a moderate
tic for stellar activity with a photometric campaign with Euler or long period, we do find corresponding changes neither in BIS
Telescope (La Silla). The periodogram of the photometry shows nor FWHM. As for Gl 674, spectral indices or photometry are
a maximum power excess for the period 23.75 d, similar to the then more informative. For Gl 526, we do find that RV is weakly
RV periodicity. The photometry phase folded to the 23.75-d pe- correlated to Hα and that Ca II H+K index varies with a clear
riod varies with a peak-to-peak amplitude of 5% and complex 50-d period (Fig. 11). Because the observed period is similar for
patterns. We cannot ascertain the rotational period of Gl 479, but the calcium index and the RV shift, we interpret that RV changes
a 5% variability can explain the observed RV variations down to as due to magnetic activity rather than a planet.