The Solar Neighborhood XXIV. Parallax Results from the CTIOPI 0.9-m Program: Stars with $\mu$ $\ge$ 1\farcs0 yr$^{-1}$ (MOTION Sample) and Subdwarfs

TL;DR

This paper reports 41 new trigonometric parallaxes for high proper motion stars, including red dwarfs and subdwarfs, revealing new binary systems, unseen companions, and insights into their luminosity and variability.

Contribution

First trigonometric parallaxes for 24 systems, discovery of unseen companions, and analysis of variability in cool subdwarfs.

Findings

24 systems have their first parallax measurements.

Discovered unseen companions in two systems.

Cool subdwarfs are less photometrically variable than main sequence stars.

Abstract

We present 41 trigonometric parallaxes of 37 stellar systems, most of which have proper motions greater than 1\farcs0 yr$^{-1}$. These are the first trigonometric parallaxes for 24 systems. Overall, there are 15 red dwarf systems and 22 red subdwarf systems in the sample. Five of the systems are multiples with directly detected companions, and we have discovered perturbations caused by unseen companions in two additional cases, the dwarf LHS 501 and the subdwarf LHS 440. The latter system may eventually provide important dynamical mass points on the subdwarf mass-luminosity relation. Two additional stars of note are LHS 272, the third closest M-type subdwarf at a distance of only 13.6 pc, and LHS 2734AB, a high velocity subdwarf binary with $V_{tan}>$ 700 km/sec, which likely exceeds the escape velocity of the Milky Way. We also report the first long term variability study of cool subdwarfs indicating that cool subdwarfs are less photometrically variable than their main sequence counterparts.