The Solar Neighborhood XLVII: Comparing M Dwarf Models with Hubble Space Telescope Dynamical Masses and Spectroscopy

TL;DR

This study tests various M dwarf evolutionary models against precise HST spectroscopic and dynamical mass data, revealing limited agreement and highlighting the models' strengths and weaknesses in predicting stellar properties.

Contribution

It provides a comprehensive comparison of five different evolutionary models with observational data for M dwarfs, assessing their accuracy and consistency.

Findings

Marginal agreement between models and observations.

Few models satisfy coevality condition consistently.

Comparison highlights strengths and weaknesses of each model family.

Abstract

We use HST/STIS optical spectroscopy of ten M dwarfs in five closely separated binary systems to test models of M dwarf structure and evolution. Individual dynamical masses ranging from 0.083 to 0.405 Mo for all stars are known from previous work. We first derive temperature, radius, luminosity, surface gravity, and metallicity by fitting the BT-Settl atmospheric models. We verify that our methodology agrees with empirical results from long baseline optical interferometry for stars of similar spectral types. We then test whether or not evolutionary models can predict those quantities given the stars' known dynamical masses and the conditions of coevality and equal metallicity within each binary system. We apply this test to five different evolutionary model sets: the Dartmouth models, the MESA/MIST models, the models of Baraffe et al. 2015, the PARSEC models, and the YaPSI models. We find marginal agreement between evolutionary model predictions and observations, with few cases where the models respect the condition of coevality in a self-consistent manner. We discuss the pros and cons of each family of models and compare their predictive power.