Benchmark stars for mean stellar density and surface gravity estimates of solar-type stars

ABSTRACT Adding an independent estimate of the mean stellar density, $\rho _{\star }$, as a constraint in the analysis of stars that host transiting exoplanets can significantly improve the precision of the planet radius estimate in cases where the light curve is too noisy to yield an accurate value of the transit impact parameter, e.g. the light curves of Earth-size planets orbiting in the habitable zone of Sun-like stars that will be obtained by the PLAnetary Transits and Oscillations of stars (PLATO) mission. I have compiled a sample of 36 solar-type stars for which analysis of high-quality light curves together with constraints on the orbital eccentricity yield mean stellar density measurements with a median error of 2.3 per cent. Of these, 8 are in transiting exoplanet systems and 28 in eclipsing binary systems with very low mass companions that contribute <0.1 per cent of the total flux in the V band. A recalibrated empirical relation for stellar mass as a function of T$_{\rm eff}$, $\rho _{\star }$, and [Fe/H] has been used to find mass estimates with a typical precision of 5.2 per cent for the stars in this sample. Examples are given of how this sample can be used to test the accuracy and precision of $\rho _{\star }$ and $\log g$ estimates from catalogues of stellar parameters for solar-type stars.