Fundamental Properties of Low-Mass Stars and Brown Dwarfs

TL;DR

This paper reviews recent progress in measuring fundamental properties of low-mass stars and brown dwarfs, emphasizing the importance of these measurements for testing theoretical models and understanding their formation and evolution.

Contribution

It summarizes current observational techniques and findings that constrain the physics of low-mass objects, highlighting advances and remaining challenges in the field.

Findings

Increased number of mass, radius, and age measurements constrains models.

Eclipsing binaries and astrometric solutions are key methods.

New surveys are discovering more benchmark systems.

Abstract

Precise measurements of the fundamental properties of low-mass stars and brown dwarfs are key to understanding the physics underlying their formation and evolution. While there has been great progress over the last decade in studying the bulk spectrophotometric properties of low-mass objects, direct determination of their masses, radii, and temperatures have been very sparse. Thus, theoretical predictions of low-mass evolution and ultracool atmospheres remain to be rigorously tested. The situation is alarming given that such models are widely used, from the determination of the low-mass end of the initial mass function to the characterization of exoplanets. An increasing number of mass, radius, and age determinations are placing critical constraints on the physics of low-mass objects. A wide variety of approaches are being pursued, including eclipsing binary studies, astrometric-spectroscopic orbital solutions, interferometry, and characterization of benchmark systems. In parallel, many more systems suitable for concerted study are now being found, thanks to new capabilities spanning both the very widest (all-sky surveys) and very narrowest (diffraction-limited adaptive optics) areas of the sky. This Cool Stars 15 splinter session highlighted the current successes and limitations of this rapidly growing area of precision astrophysics.