RED GIANT STARS FROM SLOAN DIGITAL SKY SURVEY. I. THE GENERAL FIELD

We have obtained a sample of ~22,000 red giant branch (RGB) stars based on stellar parameters, provided by the ninth data release of the Sloan Digital Sky Survey, and the CH(G)/MgH indices, measured from the included spectra. Excluding these substructures, a sample of ~16,000 RGB stars from the general field is used to investigate the properties of the thick disk, the inner halo, and the outer halo of our Galaxy. The metallicity and rotational velocity distributions are investigated for stars at 0 kpc < |Z| < 10 kpc. It is found that the canonical thick disk dominates at 0 kpc < |Z| < 2 kpc and its contribution becomes negligible at |Z| > 3 kpc. The MWTD is present and overlaps with the inner halo at 1 kpc < |Z| < 3 kpc. The transition point from the inner to the outer halo is located at |Z| ~ 20 kpc and RR ~ 35 kpc.