# 20.14.3 gold_sample_fgkm_stars

A golden sample of F, G, K and M type stars.

Stellar astrophysical parameters of the golden sample of F, G, K, and M stars from Gaia Collaboration et al. (2023c). Values are identical to the ones in the astrophysical_parameters and astrophysical_parameters_supp tables, but only those values retained after filtering are copied over.

Columns description:

A unique single numerical identifier of the source obtained from gaia_source (for a detailed description see gaia_source.source_id).

teff_gspphot : Effective temperature from GSP-Phot Aeneas best library using BP/RP spectra (float, Temperature[K])

Effective temperature (assuming source is a single star) inferred by GSP-Phot Aeneas from BP/RP spectra, apparent G magnitude and parallax. This is the median of the MCMC samples. Taken from best library that achieves the highest goodness-of-fit value.

logg_gspphot : Surface gravity from GSP-Phot Aeneas best library using BP/RP spectra (float, GravitySurface[log cgs])

Surface gravity (assuming source is a single star) inferred by GSP-Phot Aeneas from BP/RP spectra, apparent G magnitude and parallax. This is the median of the MCMC samples. Taken from best library that achieves the highest goodness-of-fit value.

mh_gspphot : Global metallicity from GSP-Phot Aeneas best library using BP/RP spectra (float, Abundances[dex])

Global metallicity (assuming source is a single star) inferred by GSP-Phot Aeneas from BP/RP spectra, apparent G magnitude and parallax. This is the median of the MCMC samples. Taken from best library that achieves the highest goodness-of-fit value.

ag_gspphot : Extinction in G band from GSP-Phot Aeneas best library using BP/RP spectra (float, Magnitude[mag])

Broadband extinction in G band (assuming source is a single star) inferred by GSP-Phot Aeneas from BP/RP spectra, apparent G magnitude and parallax. This is the median of the MCMC samples. Taken from best library that achieves the highest goodness-of-fit value.

ebpminrp_gspphot : Reddening E(BP-RP) from GSP-Phot Aeneas best library using BP/RP spectra (float, Magnitude[mag])

Reddening E(BP-RP) (assuming source is a single star) inferred by GSP-Phot Aeneas from BP/RP spectra, apparent G magnitude and parallax. This is the median of the MCMC samples. Taken from best library that achieves the highest goodness-of-fit value. Note that while $E(BP-RP)={A}_{BP}-{A}_{RP}$, this was computed at the level of MCMC samples. Hence, this relation is not exactly true for the median values.

alphafe_gspspec : Median abundance of alpha-elements [alphe/Fe] with respect to iron from GSP-Spec MatisseGauguin using RVS spectra and monte carlo realizations (float, Abundances[dex])

Abundance of alpha-elements with respect to iron (assuming source is a single star) inferred by GSP-Spec Matisse from RVS spectra.

teff_gspspec : Median value of the effective temperature from GSP-Spec MatisseGauguin monte carlo realizations using RVS spectra (float, Temperature[K])

Effective temperature (assuming source is a single star) inferred by GSP-Spec Matisse from RVS spectra.

logg_gspspec : Median value of logarithm of the stellar surface gravity using RVS spectra and monte carlo realizations (float, GravitySurface[log cgs])

Surface gravity (assuming source is a single star) inferred by GSP-Spec Matisse from RVS spectra.

mh_gspspec : Median global metallicity [M/H] from GSP-Spec MatisseGauguin using RVS spectra and monte carlo realizations (float, Abundances[dex])

Global metallicity (assuming source is a single star) inferred by GSP-Spec Matisse from RVS spectra.

radius_flame : Radius of the star derived from FLAME using teff_gspphot and lum_flame (float, Length & Distance[Solar Radius])

The radius of the star from FLAME, derived from teff_gspphot and lum_flame and associated uncertainties. It is defined as the median value (50${}^{th}$ percentile) of the distribution from sampling.

lum_flame : Luminosity of the star from FLAME using G band magnitude, extinction (ag_gspphot), parallax and a bolometric correction (bc_flame) (float, Luminosity[Solar Luminosity])

Luminosity of the star from FLAME using G band magnitude, extinction from GSP-Phot (ag_gspphot), parallax and a bolometric correction bc_flame. It is defined as the median value (50${}^{th}$ percentile) of the distribution from sampling. The bolometric correction depends on the effective temperature, metallicity and surface gravity, and these are taken from GSP-Phot. The bolometric magnitude of the Sun = 4.74 mag, and the reference absolute G-band magnitude of the Sun is 4.66 mag.

mass_flame : Mass of the star from FLAME using stellar models, lum_flame, and teff_gspphot (float, Mass[Solar Mass])

Mass of the star from FLAME.
It is defined as the median value (50${}^{th}$ percentile) of the 1D projected distribution from sampling in mass and age.
It is derived by comparing teff_gspphot and lum_flame to the BASTI solar metallicity stellar evolution models, see 11.3.6 for details.

age_flame : Age of the star from FLAME using stellar models, see mass_flame for details (float, Time[Gyr])

Age of the star from FLAME. It is defined as the median value (50${}^{th}$ percentile) of the 1D projected distribution from sampling in mass and age, see mass_flame for details.

evolstage_flame : Evolutionary stage of the star derived from FLAME using stellar models, see mass_flame for details (int)

Evolution stage of the star from FLAME. It is defined using the median value (50${}^{th}$ percentile) of the 1D projected distribution from sampling in mass and age, see mass_flame for details. The value is adopted from the BASTI model grid (Hidalgo et al. 2018) using the following convention: $100=$ ZAMS, $300=$ first minimum of T${}_{\mathrm{eff}}$ for high-mass or central H mass-fraction, ${X}_{c}$, = 0.30, $360=$ main sequence turn-off, $420={X}_{c}=0.00$, $490=$ base of the red giant branch (RGB), $860=$ maximum $\mathcal{L}$ along the RGB bump, 890 = minimum $\mathcal{L}$ along the RGB bump, 1290 = tip of the RGB.

radius_flame_spec : Radius of the star from FLAME using teff_gspspec and lum_flame_spec (float, Length & Distance[Solar Radius])

The radius of the star from FLAME, derived from teff_gspspec and lum_flame_spec using the Stefan-Boltzmann law with a solar effective temperature of 5772 K, see Section 1.2.3, and associated uncertainties. It is defined as the median value (50${}^{th}$ percentile) of the distribution from sampling.

lum_flame_spec : Luminosity of the star from FLAME using G band magnitude, extinction (ag_gspphot), parallax and a bolometric correction (bc_flame_spec) (float, Luminosity[Solar Luminosity])

Luminosity of the star from FLAME using G band magnitude, extinction from GSP-Phot (ag_gspphot), parallax and a bolometric correction bc_flame_spec.
It is defined as the median value (50${}^{th}$ percentile) of the distribution from sampling.
The bolometric correction depends on the effective temperature, metallicity and surface gravity, and these are based on GSP-Spec values in table astrophysical_parameters.
The bolometric magnitude of the Sun = 4.74 mag, see Section 1.2.3 and the reference absolute G-band magnitude of the Sun is 4.66 mag, see Section 11.3.6.

mass_flame_spec : Mass of the star from FLAME using stellar models, lum_flame_spec, and teff_gspspec (float, Mass[Solar Mass])

Mass of the star from FLAME.
It is defined as the median value (50${}^{th}$ percentile) of the 1D projected distribution from sampling in mass and age.
It is derived by comparing teff_gspspec and lum_flame_spec to the BASTI solar metallicity stellar evolution models, see 11.3.6 for details.

age_flame_spec : Age of the star from FLAME using stellar models, see mass_flame_spec for details (float, Time[Gyr])

Age of the star from FLAME. It is defined as the median value (50${}^{th}$ percentile) of the 1D projected distribution from sampling in mass, age, and metallicity, see mass_flame_spec for details.

evolstage_flame_spec : Evolutionary stage of the star derived from FLAME using stellar models, see mass_flame_spec for details (int)

Evolution stage of the star from FLAME using GSP-Spec T${}_{\mathrm{eff}}$, teff_gspspec.
It is defined using the median value (50${}^{th}$ percentile) of the 1D projected distribution from sampling in mass and age, see mass_flame_spec for details.
The value is adopted from the BASTI model grid (Hidalgo et al. 2018) using the following convention: $100=$ ZAMS, $300=$ first minimum of T${}_{\mathrm{eff}}$ for high-mass or central H mass-fraction, ${X}_{c}$, = 0.30, $360=$ main sequence turn-off, $420={X}_{c}=0.00$, $490=$ base of the red giant branch (RGB), $860=$ maximum $\mathcal{L}$ along the RGB bump, 890 = minimum $\mathcal{L}$ along the RGB bump, 1290 = tip of the RGB.

ESP-HS aims to only process A,B, and O stars. Therefore, during the selection procedure, a random forest algorithm, trained on simulated BP/RP data, provides a coarse estimate of the spectral type (O,B,A,F,G, or KM).