Reevaluating the Mass-Radius Relation for Low-Mass, Main Sequence Stars

TL;DR

This study compares observed data of low-mass main sequence stars with new stellar models, finding improved agreement and reducing previous discrepancies in the mass-radius relationship.

Contribution

It introduces a comprehensive grid of stellar evolution models accounting for age and metallicity variations, enhancing the match with observational data.

Findings

Models match observed radii within 4% for most stars

Mean absolute error in radius is 2.3%

Agreement improved by a factor of two over previous studies

Abstract

We examine the agreement between the observed and theoretical low-mass (< 0.8 solar masses) stellar main sequence mass-radius relationship by comparing detached eclipsing binary (DEB) data with a new, large grid of stellar evolution models. The new grid allows for a realistic variation in the age and metallicity of the DEB population, characteristic of the local galactic neighborhood. Overall, our models do a reasonable job of reproducing the observational data. A large majority of the models match the observed stellar radii to within 4%, with a mean absolute error of 2.3%. These results represent a factor of two improvement compared to previous examinations of the low-mass mass-radius relationship. The improved agreement between models and observations brings the radius deviations within the limits imposed by potential starspot-related uncertainties for 92% of the stars in our DEB sample.