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

TL;DR

This paper compiles a sample of 36 solar-type stars with precise stellar density measurements to improve exoplanet radius estimates, and introduces a recalibrated empirical relation for stellar mass based on multiple parameters.

Contribution

It provides a new sample of stars with accurate density measurements and a recalibrated mass relation, enhancing stellar parameter estimates for solar-type stars.

Findings

Median density measurement error of 2.3% for the sample

Mass estimates with typical 5.2% precision using the new relation

Sample includes stars in transiting exoplanet and eclipsing binary systems

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 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%. Of these, 8 are in transiting exoplanet systems and 28 in eclipsing binary systems with very low mass companions that contribute <0.1% of the total flux in the V band. A re-calibrated 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% 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.