A metallicity , chemical composition , and kinematic survey has been conducted for a sample of 340 candidate field red horizontal branch stars .
High resolution , high signal-to-noise spectra were gathered with the McDonald Observatory 2.7m Tull and the Hobby-Eberly Telescope echelle spectrographs , and were used to determine effective temperatures , surface gravities , microturbulent velocities , [ Fe/H ] metallicities , and abundance ratios [ X/Fe ] for seven \alpha and Fe-group species .
The derived temperatures and gravities confirm that at least half of the candidates are true RHB stars , with ( average ) parameters T _ { eff } \sim 5000 K , log g \sim 2.5 .
From the \alpha abundances alone the thin and thick Galactic populations are apparent in our sample .
Space motions for 90 % of the program stars were computed from Hipparcos and Gaia parallaxes and proper motions .
Correlations between chemical compositions and Galactic kinematics clearly indicate the existence of both thin and thick disk RHB stars .