A Spectroscopic Survey of Field Red Horizontal-Branch Stars
  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 Teff$\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.
