Accurate masses of very low mass stars: IV Improved mass-luminosity relations

TL;DR

This paper provides improved empirical mass-luminosity relations for very low mass stars, highlighting the accuracy of infrared relations and discrepancies in V band predictions, impacting stellar mass function studies.

Contribution

It offers new, highly accurate mass measurements and refined empirical relations, especially in the infrared, with comparisons to theoretical models and implications for stellar population analysis.

Findings

Infrared relations are tighter than V band due to metallicity effects.

Good agreement with theoretical models in infrared, but discrepancies in V band for low-mass stars.

Refined mass-luminosity relations improve stellar mass function estimates.

Abstract

We present improved visual and near-infrared empirical mass-luminosity relations for very low mass stars (M$<$0.6~\Msol). These relations make use of all stellar masses in this range known with better than 10% accuracy, most of which are new determinations with 0.2 to 5% accuracy from our own programme, presented in a companion paper. As predicted by stellar structure models, the metallicity dispersion of the field populations induces a large scatter around the mean V band relation, while the infrared relations are much tighter. The agreement of the observed infrared mass-luminosity relations with the theoretical relations of Baraffe et al. (1998) and Siess et al. (2000) is impressive, while we find an increasingly significant discrepancy in the V band for decreasing masses. The theoretical mass-luminosity relation which is insufficiently steep, and has introduced some errors in the local stellar mass functions derived from V band luminosity functions.