2008ApJ...689..416B

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 to 0.8. This corresponds to secondary masses as small as ∼0.15 M_☉. 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.