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

Abstract

M dwarfs with masses 0.1 ≤ M/M ≤ 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 ≤ 0.3 and with trigonometric distances placing them within 15 pc (π trig ≥ 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 V J R KC I KC 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 ≤ 0.3 are found in multiple systems with primary stars of all masses within 15 pc.

A million binaries from Gaia eDR3: sample selection and validation of Gaia parallax uncertainties

“…When all members of multiple systems are counted individually, the total stellar space density in the solar neighborhood is about 0.10 pc −3 (e.g. Winters et al 2020).…”