The space interferometry mission astrometric grid giant star survey. iii. basic stellar parameters for an extended sample

We present results of high-resolution (∼55000) spectral observations of 830 photometrically pre-selected candidate red giants in the magnitude range of V = 9-12. We develop a pipeline for automated determination of the stellar atmospheric parameters from these spectra and estimate T_eff, logg, [Fe/H], microturbulence velocity, and projected rotational velocities, v sin i, for the stars. The analysis confirms that the candidate selection procedure yielded red giants with very high success rate. We show that most of these stars are G and K giants with slightly subsolar metallicity ([Fe/H]∼-0.3 dex). An analysis of Mg abundances in the sample results in consistency of the [Mg/Fe] vs [Fe/H] trend with published results.