14.1.8 Astrophysical Parameters

Gaia DR3 presents astrophysical parameters for 1590 M sources based on the BP/RP spectra, the RVS spectra, and the BP/RP photometry. It is a very rich, very ambitious, and very complex dataset, as explained in Chapter 11, containing results from many different pipelines.

In addition to the validation presented in Babusiaux et al. (2023), we discuss below some additional results:

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  The rather strong correlation between absorption and temperature seen in Gaia DR2 is now less pronounced, cf. Section 14.2.8.

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  Comparing with the GOG20 model, Section 14.3.7 and Section 14.3.8, we notice:

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    The overall agreement between data and model is good but differences can be large in the Galactic plane, linked to the extinction.

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    The $[\mathrm{M}/\mathrm{H}]$ and $[\alpha /\mathrm{Fe}]$ determinations seem to suffer from correlation with the extinction.

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    The high number of large $A_{\mathrm{G}}$ values, including at high galactic latitudes, is questionable.

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    The $[\mathrm{M}/\mathrm{H}]$ shows a low-metallicity tail not expected from the simulation.

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    The $[\alpha /\mathrm{Fe}]$ distribution is narrower than the simulated one, with no value smaller than -0.1 dex or greater than 0.4 dex.

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    Numerous high-mass young stars, on the giant branch, are not predicted by the model. This is due to missing or incorrect model templates for the determination of the age and mass for giants.

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  From tests using star clusters, Section 14.7.4 and Section 14.7.5, we notice:

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    mh_gspphot has a clear negative bias as compared to literature values.

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    distance_gspphot is overestimated for distant clusters (beyond 1–2$\mathrm{kpc}$) as compared to literature values.

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    Trends in abundances in GSP-Spec data are discussed in Section 14.7.5.

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    $T_{\mathrm{eff}}$, $\log g$ and $[\mathrm{M}/\mathrm{H}]$ show systematic differences between GSP-Phot and GSP-Spec.