The Volume-Complete Sample of M Dwarfs with Masses 0.1 <= M/M_sol <= 0.3 within 15 Parsecs

TL;DR

This paper provides a comprehensive volume-complete list of 512 M dwarfs within 15 parsecs, analyzes their mass function, multiplicity rate, and presents new photometry, aiding astrophysical studies of low-mass stars and exoplanet atmospheres.

Contribution

It offers the first volume-complete, all-sky catalog of low-mass M dwarfs within 15 pc, including new photometry and multiplicity statistics.

Findings

Mass function increases with decreasing mass in linear space.

Multiplicity rate of primary M dwarfs is approximately 21%.

43% of M dwarfs are in multiple systems within 15 pc.

Abstract

M dwarfs with masses 0.1 <= M/M_sol <= 0.3 are under increasing scrutiny because these fully convective stars pose interesting astrophysical questions regarding their magnetic activity and angular momentum history. They also afford the most accessible near-future opportunity to study the atmospheres of terrestrial planets. Because they are intrinsically low in luminosity, the identification of the nearest examples of these M dwarfs is essential for progress. We present the volume-complete, all-sky list of 512 M dwarfs with masses 0.1 <= M/M_sol <= 0.3 and with trigonometric distances placing them within 15 pc (parallax >= 66.67 mas) from which we have created a sample of 413 M dwarfs for spectroscopic study. We present the mass function for these 512 M dwarfs, which increases with decreasing stellar mass in linear mass space, but is flat in logarithmic mass space. As part of this sample, we present new VRI photometry for 17 targets, measured as a result of the RECONS group's long-term work at the CTIO/SMARTS 0.9m telescope. We also note the details of targets that are known to be members of multiple systems and find a preliminary multiplicity rate of 21 +/- 2% for the primary M dwarfs in our sample, when considering known stellar and brown dwarf companions at all separations from their primaries. We further find that 43 +/- 2% of all M dwarfs with masses 0.1 <= M/M_sol <= 0.3 are found in multiple systems with primary stars of all masses within 15 pc.