The Detection of Low Mass Companions in Hyades Cluster Spectroscopic Binary Stars

TL;DR

This study uses high-resolution infrared spectroscopy to detect low-mass companions in Hyades binary stars, deriving mass ratios and estimating component masses to understand binary star formation.

Contribution

It presents new double-lined solutions for 25 binaries, including the first detection of a potential brown dwarf companion, expanding knowledge of binary mass distributions.

Findings

Mass ratios range from ~0.1 to 0.8.

Detected a potential brown dwarf companion with q=0.06.

Produced initial distributions of mass ratios and secondary masses.

Abstract

We have observed a large sample of spectroscopic binary stars in the Hyades Cluster, using high resolution infrared spectroscopy to detect low mass companions. We combine our double-lined infrared measurements with well constrained orbital parameters from visible light single-lined observations to derive dynamical mass ratios. Using these results, along with photometry and theoretical mass-luminosity relationships, we estimate the masses of the individual components in our binaries. In this paper we present double-lined solutions for 25 binaries in our sample, with mass ratios from ~0.1-0.8. This corresponds to secondary masses as small as ~0.15 Msun. We include here our preliminary detection of the companion to vB 142, with a very small mass ratio of q=0.06+-0.04; this indicates that the companion may be a brown dwarf. This paper is an initial step in a program to produce distributions of mass ratio and secondary mass for Hyades cluster binaries with a wide range of periods, in order to better understand binary star formation. As such, our emphasis is on measuring these distributions, not on measuring precise orbital parameters for individual binaries.