GaiaData Release 3

Abstract

Context. The astrophysical characterisation of sources is among the major new data products in the third Gaia data release (DR3). In particular, there are stellar parameters for 471 million sources estimated from low-resolution BP/RP spectra. Aims. We present the General Stellar Parameterizer from Photometry (GSP-Phot), which is part of the astrophysical parameters inference system (Apsis). GSP-Phot is designed to produce a homogeneous catalogue of parameters for hundreds of millions of single non-variable stars based on their astrometry, photometry, and low-resolution BP/RP spectra. These parameters are effective temperature, surface gravity, metallicity, absolute M G magnitude, radius, distance, and extinction for each star. Methods. GSP-Phot uses a Bayesian forward-modelling approach to simultaneously fit the BP/RP spectrum, parallax, and apparent G magnitude. A major design feature of GSP-Phot is the use of the apparent flux levels of BP/RP spectra to derive, in combination with isochrone models, tight observational constraints on radii and distances. We carefully validate the uncertainty estimates by exploiting repeat Gaia observations of the same source.Results. The data release includes GSP-Phot results for 471 million sources with G < 19. Typical differences to literature values are 110 K for T eff and 0.2-0.25 for log g, but these depend strongly on data quality. In particular, GSP-Phot results are significantly better for stars with good parallax measurements ( /σ > 20), mostly within 2kpc. Metallicity estimates exhibit substantial biases compared to literature values and are only useful at a qualitative level. However, we provide an empirical calibration of our metallicity estimates that largely removes these biases. Extinctions A 0 and A BP show typical differences from reference values of 0.07-0.09 mag. MCMC samples of the parameters are also available for 95% of the sources. Conclusions. GSP-Phot provides a homogeneous catalogue of stellar parameters, distances, and extinctions that can be used for various purposes, such as sample selections (OB stars, red giants, solar analogues etc.). In the context of asteroseismology or ground-based interferometry, where targets are usually bright and have good parallax measurements, GSP-Phot results should be particularly useful for combined analysis or target selection.

Variability of Magnetic Hot Stars from the TESS Observations

“…We used the ATLAS9 SED Grid (Castelli et al 1997) for mCP stars with the effective temperatures ranging from 8000-15,000 K and surface gravities log g (cgs) from 3.5-5. Andrae et al (2023) noted that the distance assessments by Bailer-Jones et al (2021) outperform GSP-Phot distances. Consequently, we have determined the distances to the stars in our sample using the results derived by Bailer-Jones et al (2021).…”

Young Stellar Object Candidates in IC 417

“…In Bailer-Jones et al (2021), two distances are provided, geometric and photogeometric. In DR3 itself, a distance is provided from the General Stellar Parameterizer from Photometry ("GSP-Phot;" Andrae et al 2023). All of these methods have limitations, particularly when the fractional uncertainty in the parallax is large, and they may not do well much past 2 kpc in general.…”

Dynamical Origin for the Collinder 132–Gulliver 21 Stream: A Mixture of Three Comoving Populations with an Age Difference of 250 Myr

“…With the release of Gaia DR3, astrophysical parameters have become available; these are either derived from RVS spectra and/or from low-resolution (R∼40) BP/RP prism spectra (Creevey et al 2022). Astrophysical parameters determined from forward-modeling the BP/RP spectra (GSP-Phot, 470 million; Andrae et al 2022) outnumber those obtained from combined RVS spectra of single stars (GSP-Spec,6 million;Recio-Blanco et al 2022), which comes with more precise and detailed information on individual chemical abundances.…”