Line Broadening in Field Metal-poor Red Giant and Red Horizontal Branch Stars

We report 349 radial velocities for 45 metal-poor field red giant and red horizontal branch stars, with time coverage ranging from 1 to 21 years. We have identified one new spectroscopic binary, HD 4306, and one possible such system, HD 184711. We also report 57 radial velocities for 11 of the 91 stars reported on previously by Carney et al. (2003). All but one of the 11 stars had been found to have variable radial velocities. New velocities for the long-period spectroscopic binaries BD−1 2582 and HD 108317 have extended the time coverage to 21.7 and 12.5 years, respectively, but in neither case have we yet completed a full orbital period. As was found in the previous study, radial velocity “jitter” is present in many of the most luminous stars. Excluding stars showing spectroscopic binary orbital motion, all 7 of the red giants with estimated MV values more luminous than −2.0 display jitter, as well as 3 of the 14 stars with −2.0 < MV ≤ −1.4. We have also measured the line broadening in all the new spectra, using synthetic spectra as templates. Comparison with results from high-resolution and higher signal-to-noise (S/N) spectra employed by other workers shows good agreement