Parameters of 220 million stars from Gaia BP/RP spectra

Understand

We develop, validate and apply a forward model to estimate stellar atmospheric parameters ($T_{\rm eff}$, $\log{g}$ and $\mathrm{[Fe/H]}$), revised distances and extinctions for 220 million stars with XP spectra from $\textit{Gaia}$ DR3.

• Instead of using $\textit{ab initio}$ stellar models, we develop a data-driven model of $\textit{Gaia}$ XP spectra as a function of the stellar parameters, with a few straightforward built-in physical assumptions.
• We train our model on stellar atmospheric parameters from the LAMOST survey, which provides broad coverage of different spectral types.
• We model the $\textit{Gaia}$ XP spectra with all of their covariances, augmented by 2MASS and WISE photometry that greatly reduces degeneracies between stellar parameters, yielding more precise determinations of temperature and dust reddening.