Stellar ages, masses, extinctions, and orbital parameters based on spectroscopic parameters of Gaia DR3 (original) (raw)
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The promise of Gaia and how it will influence stellar ages
Proceedings of the International Astronomical Union, 2008
The Gaia space project, planned for launch in 2011, is one of the ESA cornerstone missions, and will provide astrometric, photometric and spectroscopic data of very high quality for about one billion stars brighter than V = 20. This will allow to reach an unprecedented level of information and knowledge on several of the most fundamental astrophysical issues, such as mapping of the Milky Way, stellar physics (classification and parameterization), Galactic kinematics and dynamics, study of the resolved stellar populations in the Local Group, distance scale and age of the Universe, dark matter distribution (potential tracers), reference frame (quasars, astrometry), planet detection, fundamental physics, Solar physics, Solar system science.I will present a description of the instrument and its main characteristics, and discuss a few specific science cases where Gaia data promise to contribute fundamental improvement within the scope of this Symposium.
Gaia Data Release 3: A Golden Sample of Astrophysical Parameters
arXiv (Cornell University), 2022
Context. Gaia Data Release 3 (DR3) provides a wealth of new data products for the astronomical community to exploit, including astrophysical parameters for a half billion stars. In this work we demonstrate the high quality of these data products and illustrate their use in different astrophysical contexts. Aims. We produce homogeneous samples of stars with high quality astrophysical parameters by exploiting Gaia DR3 while focusing on many regimes across the Hertzsprung-Russell (HR) diagram; spectral types OBA, FGKM, and ultra-cool dwarfs (UCDs). We also focus on specific sub-samples which are of particular interest to the community: solar analogues, carbon stars, and the Spectro Photometric Standard Stars (SPSS). Methods. We query the astrophysical parameter tables along with other tables in Gaia DR3 to derive the samples of the stars of interest. We validate our results by using the Gaia catalogue itself and by comparison with external data. Results. We have produced six homogeneous samples of stars with high quality astrophysical parameters across the HR diagram for the community to exploit. We first focus on three samples that span a large parameter space: young massive disk stars (OBA, ∼3M), FGKM spectral type stars (∼3M), and UCDs (∼20 K). We provide these sources along with additional information (either a flag or complementary parameters) as tables that are made available in the Gaia archive. We furthermore identify 15 740 bone fide carbon stars, 5 863 solar-analogues, and provide the first homogeneous set of stellar parameters of the SPSS sample. We demonstrate some applications of these samples in different astrophysical contexts. We use a subset of the OBA sample to illustrate its usefulness to analyse the Milky Way rotation curve. We then use the properties of the FGKM stars to analyse known exoplanet systems. We also analyse the ages of some unseen UCD-companions to the FGKM stars. We additionally predict the colours of the Sun in various passbands (Gaia, 2MASS, WISE) using the solar-analogue sample. Conclusions. Gaia DR3 contains a wealth of new high quality astrophysical parameters for the community to exploit.
Stellar mass and age determinations
Astronomy & Astrophysics, 2012
Aims. We present dense grids of stellar models suitable for comparison with observable quantities measured with great precision, such as those derived from binary systems or planet-hosting stars. Methods. We computed new Geneva models without rotation at metallicities Z = 0.006, 0.01, 0.014, 0.02, 0.03 and 0.04 (i.e. [Fe/H] from −0.33 to +0.54) and with mass in small steps from 0.5 to 3.5 M . Great care was taken in the procedure for interpolating between tracks in order to compute isochrones. Results. Several properties of our grids are presented as a function of stellar mass and metallicity. Those include surface properties in the Hertzsprung-Russell diagram, internal properties including mean stellar density, sizes of the convective cores, and global asteroseismic properties. Conclusions. We checked our interpolation procedure and compared interpolated tracks with computed tracks. The deviations are less than 1% in radius and effective temperatures for most of the cases considered. We also checked that the present isochrones provide nice fits to four couples of observed detached binaries and to the observed sequences of the open clusters NGC 3532 and M67. Including atomic diffusion in our models with M < 1.1 M leads to variations in the surface abundances that should be taken into account when comparing with observational data of stars with measured metallicities. For that purpose, iso-Z surf lines are computed. These can be requested for download from a dedicated web page together with tracks at masses and metallicities within the limits covered by the grids. The validity of the relations linking Z and [Fe/H] is also re-assessed in light of the surface abundance variations in low-mass stars.
Astrophysical Journal, 2006
We present an empirical method to derive photometric metallicity, reddening, and distance to old stellar populations by using a few major features of the red giant branch (RGB) in near-IR color-magnitude diagrams. We combine the observed RGB features with a set of equations linking the global metallicity [M/H] to suitable RGB parameters (colors, magnitudes, and slope), as calibrated from a homogeneous sample of Galactic globular clusters with different metallicities. This technique can be applied to efficiently derive the main population parameters of old stellar systems, with the goal of using ground-based adaptive optics and space facilities to probe the stellar content of remote galaxies.
GAIA: Composition, formation and evolution of the Galaxy
Astronomy and Astrophysics, 2001
The GAIA astrometric mission has recently been approved as one of the next two 'cornerstones' of ESA's science programme, with a launch date target of not later than mid-2012. GAIA will provide positional and radial velocity measurements with the accuracies needed to produce a stereoscopic and kinematic census of about one billion stars throughout our Galaxy (and into the Local Group), amounting to about 1 per cent of the Galactic stellar population. GAIA's main scientific goal is to clarify the origin and history of our Galaxy, from a quantitative census of the stellar populations. It will advance questions such as when the stars in our Galaxy formed, when and how it was assembled, and its distribution of dark matter. The survey aims for completeness to V = 20 mag, with accuracies of about 10 µas at 15 mag. Combined with astrophysical information for each star, provided by on-board multi-colour photometry and (limited) spectroscopy, these data will have the precision necessary to quantify the early formation, and subsequent dynamical, chemical and star formation evolution of our Galaxy. Additional products include detection and orbital classification of tens of thousands of extra-Solar planetary systems, and a comprehensive survey of some 10 5 − 10 6 minor bodies in our Solar System, through galaxies in the nearby Universe, to some 500 000 distant quasars. It will provide a number of stringent new tests of general relativity and cosmology. The complete satellite system was evaluated as part of a detailed technology study, including a detailed payload design, corresponding accuracy assesments, and results from a prototype data reduction development.
Monthly Notices of the Royal Astronomical Society
Understanding the formation and evolution of our Galaxy requires accurate distances, ages and chemistry for large populations of field stars. Here we present several updates to our spectro-photometric distance code, that can now also be used to estimate ages, masses, and extinctions for individual stars. Given a set of measured spectrophotometric parameters, we calculate the posterior probability distribution over a given grid of stellar evolutionary models, using flexible Galactic stellar-population priors. The code (called StarHorse) can acommodate different observational datasets, prior options, partially missing data, and the inclusion of parallax information into the estimated probabilities. We validate the code using a variety of simulated stars as well as real stars with parameters determined from asteroseismology, eclipsing binaries, and isochrone fits to star clusters. Our main goal in this validation process is to test the applicability of the code to field stars with known Gaia-like parallaxes. The typical internal precision (obtained from realistic simulations of an APOGEE+Gaia-like sample) are 8% in distance, 20% in age, 6% in mass, and 0.04 mag in A V. The median external precision (derived from comparisons with earlier work for real stars) varies with the sample used, but lies in the range of [0, 2]% for distances, [12, 31]% for ages, [4, 12]% for masses, and 0.07 mag for A V. We provide StarHorse distances and extinctions for the APOGEE DR14, RAVE DR5, GES DR3 and GALAH DR1 catalogues.
Astronomy & Astrophysics, 2019
A deep understanding of the Milky Way galaxy, its formation and evolution requires observations of huge numbers of stars. Stellar photometry, therefore, provides an economical method to obtain intrinsic stellar parameters. With the addition of distance information – a prospect made real for more than a billion stars with the second Gaia data release – deriving reliable ages from photometry is a possibility. We have developed a Bayesian method that generates 2D probability maps of a star’s age and metallicity from photometry and parallax using isochrones. Our synthetic tests show that including a near-UV passband enables us to break the degeneracy between a star’s age and metallicity for certain evolutionary stages. It is possible to find well-constrained ages and metallicities for turn-off and sub-giant stars with colours including a U band and a parallax with uncertainty less than ∼20%. Metallicities alone are possible for the main sequence and giant branch. We find good agreement ...
AGB Stars as Tracers of Star Formation Histories: Implications for GAIA Photometry and Spectroscopy
We argue that tracing star formation histories with ESA's space mission GAIA using main sequence turn-off (MSTO) point dating will mainly be effective in cases of mild interstellar extinction (E(B-V)<0.5). For higher reddenings the MSTO approach will be severely limited both in terms of traceable ages (t<0.5 Gyr at 8 kpc; E(B-V)=1.0) and/or distances (d<2 kpc for t=15 Gyr; E(B-V)=1.0), since the MSTO will be located at magnitudes too faint for GAIA. AGB stars may alternatively provide precise population ages with GAIA for a wide range of ages and metallicities, with traceable distances of up to 250 kpc at E(B-V)=0 (d=15 kpc if E(B-V)=2.0). It is essential however that effective temperatures precise to 0.01 dex, metallicities to 0.2 dex, and E(B-V) to 0.03 are derived for individual stars, in order to obtain their ages precise to 0.2 dex. This task is quite challenging for GAIA photometry and spectroscopy, though preliminary tests show that comparable precisions may be a...
Spectral Energy Distributions and Age Estimates of 40 massive young stellar objects
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Spectral Energy Distributions and Age Estimates of Five Massive Young Stellar Objects
We present the spectral energy distributions (SEDs) of five massive young stellar objects (YSOs), detected fro m the NIR imaging survey carried out by Varricatt et al.[1] and estimated the physical and structural/geometrical parameters, including their ages and masses, for each of the five central YSO outflow candidates, along with their associated circu mstellar disks and infalling envelopes. The SEDs of YSOs in five massive star forming reg ions has been reconstructed using 2MASS, MSX, IRAS, IRA C & MIPS, SCUBA, WISE, SPIRE and IRAM data, partly available fro m previous works, using the on-line SED Fitting tool developed by[2],[3]. We have derived the IRA S catalogue flu xes as well as the flu xes in the Mid-IR and sub-mm/ mm, d irectly fro m the images. With the help of the analysis of SEDs and subsequently estimated parameters for the central YSO sources along with its circu mstellar d isks and envelopes, the cumulat ive d istribution of the stellar ages and masses of the massive YSOs can be analysed. This leads to a better understanding for the format ion history of massive stars in their respective star forming regions.