BEYOND THE MAIN SEQUENCE: TESTING THE ACCURACY OF STELLAR MASSES PREDICTED BY THE PARSEC EVOLUTIONARY TRACKS

Abstract

Characterizing the physical properties of exoplanets, and understanding their\nformation and orbital evolution requires precise and accurate knowledge of\ntheir host stars. Accurately measuring stellar masses is particularly important\nbecause they likely influence planet occurrence and the architectures of\nplanetary systems. Single main-sequence stars typically have masses estimated\nfrom evolutionary tracks, which generally provide accurate results due to their\nextensive empirical calibration. However, the validity of this method for\nsubgiants and giants has been called into question by recent studies, with\nsuggestions that the masses of these evolved stars could have been\noverestimated. We investigate these concerns using a sample of 59 benchmark\nevolved stars with model-independent masses (from binary systems or\nasteroseismology) obtained from the literature. We find very good agreement\nbetween these benchmark masses and the ones estimated using evolutionary\ntracks. The average fractional difference in the mass interval $\\sim$0.7 - 4.5\nM$_{\\odot}$, is consistent with zero (-1.30 $\\pm$ 2.42%), with no significant\ntrends in the residuals relative to the input parameters. A good agreement\nbetween model-dependent and -independent radii (-4.81 $\\pm$ 1.32%) and surface\ngravities (0.71 $\\pm$ 0.51%) is also found. The consistency between\nindependently determined ages for members of binary systems adds further\nsupport for the accuracy of the method employed to derive the stellar masses.\nTaken together, our results indicate that determination of masses of evolved\nstars using grids of evolutionary tracks is not significantly affected by\nsystematic errors, and is thus valid for estimating the masses of isolated\nstars beyond the main sequence.\n