20.14.1 binary_masses
Table of masses derived from the nonsingle stars (NSS) solutions with orbital parameters in the DR3 NSS two body orbit table.
The table below is described in detail in Gaia Collaboration et al. (2023a). The table presents the different types of NSS orbital solutions combined and which parameters each combination allows to constrain (orbital parameters being presented in gaiadr3.nss_two_body_orbit):
combination_method m1 m2 fluxratio Orbital+SB2 ✓ ✓ ✓ EclipsingSpectro(SB2) ✓ ✓ Eclipsing+SB2 ✓ ✓ AstroSpectroSB1+M1 ✓ ✓ Orbital+SB1+M1 ✓ ✓ EclipsingSpectro+M1 ✓ Eclipsing+SB1+M1 ✓ SB2+M1 ✓ Orbital+M1 lower/upper SB1+M1 lower
Columns description:
A unique single numerical identifier of the source obtained from gaia_source (for a detailed description see gaia_source.source_id).
Mass of the primary component. It may be either the input mass from isochrone fitting (see Appendix D of Gaia Collaboration et al. (2023a) or the mass derived directly from the NonSingle Stars (NSS) solutions for Orbital+SB2 or EclipsingSB2 combination_method.
Lower confidence level (16%) of the primary mass.
Upper confidence level (84%) of the primary mass.
Mass of the secondary component.

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For Orbital+M1 combination_method, a value is provided only when fluxratio_upper = fluxratio_lower, else only m2_lower and m2_upper are provided, according to the fluxratio_lower and fluxratio_upper tested to be compatible with both components being on the main sequence.

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For SB1+M1 combination_method, due to the unknown inclination, m2 is unknown, only m2_lower can be determined and is filled
Lower confidence level (16%) of the secondary mass.
For combination_method=SB1+M1, it corresponds to the lower confidence level (16%) of the secondary mass obtained assuming $\mathrm{sin}i=1$.
For combination_method=Orbital+M1, it corresponds to the lower confidence level (16%) of the secondary mass obtained with fluxratio_lower.
Upper confidence level (84%) of the secondary mass.
If combination_method=Orbital+M1, it corresponds to the upper confidence level (84%) of the secondary mass obtained with fluxratio_upper.
Ratio of the Gband flux of the secondary over the primary ${F}_{2}/{F}_{1}$.
It can be derived only when combining astrometric and spectroscopic solutions.
It is fixed to g_luminosity_ratio for Eclipsing binaries.
When the fluxratio can be derived using the combination of an astrometric and spectroscopic solutions, fluxratio_lower corresponds to the lower confidence level (16%) of the flux ratio derived.
For SB2+M1, Orbital+M1 and SB1+M1, fluxratio_lower corresponds to the minimum fluxratio compatible with a main sequence primary. It is used to derive m2_lower for Orbital+M1 and SB1+M1. For SB2+M1, the full range of possible fluxratio is used to derive m1_lower, m1_upper, m2_lower and m2_upper.
When the fluxratio can be derived using the combination of an astrometric and spectroscopic solutions, fluxratio_upper corresponds to the upper confidence level (84%) of the flux ratio derived.
For SB2+M1, it corresponds to the maximum fluxratio compatible with the primary being on the main sequence. The full range of possible fluxratio is used to derive m1_lower, m1_upper, m2_lower and m2_upper.
For Orbital+M1, fluxratio_upper corresponds to the maximum fluxratio compatible with both components being on the main sequence. It is used to derive m2_upper. Therefore Orbital+M1 with fluxratio_upper=0 corresponds to sources for which no fluxratio was compatible with the secondary star being on the main sequence.
Orbital+M1 with no fluxratio_upper provided corresponds to the case of ternary systems where the mass determination of the primary needed a fluxratio_lower$\mathrm{>}\mathrm{0}$ while this flux ratio was not compatible with the derived secondary mass. For those cases, both m2_upper and m2_lower are derived using fluxratio_lower.
Combination of NSS solutions which has been used to derive the values. It is a combination of the nss_solution_type from nss_two_body_orbit. SB1 corresponds to both SB1 and SB1C solutions, similarly for SB2 which contains also SB2C, and Orbital which contains OrbitalAlternative—Validated and OrbitalTargetedSearch—Validated solutions.
M1 is added when a primary mass estimation is needed. In this case the estimate of the primary mass used is provided in the m1 field.
The primary star mass provided in m1 can have several origins that can be tracked through this flag:

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none: the NonSingle Stars (NSS) solutions provide a direct estimate for the mass.

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IsocLum (see Appendix D of Gaia Collaboration et al. (2023a))

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WD fixed mass
The flag ‘AMRFClassIII’ indicates sources classified as astrometric binaries with compactobject companions by the astrometric mass ratio function (AMRF) method, see Gaia Collaboration et al. (2023a) for details.