Gaia Data Release 3. Apsis II: Stellar parameters

Context. The third Gaia data release ( DR3) contains, beyond the astrometry and photometry, dispersed light for hundreds of millions sources from prism spectra (BP RP) spectrograph (RVS). This opens a new window on chemo-dynamical properties stars in our Galaxy, essential knowledge understanding structure, formation, evolution Milky Way. Aims. To provide insight into physical Way stars, we used these to produce uniformly derived all-sky catalogue stellar astrophysical parameters: atmospheric T eff , log g [M/H], [ α /Fe], activity index, emission lines, rotation), 13 chemical abundance estimates, characteristics (radius, age, mass, bolometric luminosity), distance, dust extinction. Methods. We developed parameter inference system (Apsis) pipeline infer parameters objects by analysing their astrometry, BP/RP, RVS spectra. validate results against those other works literature, including benchmark interferometry, asteroseismology. Here assess analysis performance Apsis statistically. Results. describe quantities obtained, underlying assumptions limitations results. guidance identify regimes which should not be used. Conclusions. Despite some limitations, this is most extensive inferred date. They comprise [M/H] (470 million using 6 RVS), radius million), mass (140 age (120 abundances (5 diffuse interstellar band (half indices (2 H equivalent widths (200 further classifications spectral types (220 million) emission-line (50 thousand). More precise detailed based epoch BP, RP, spectrophotometry are planned next release.