2MASS J00184681+2121397 , the SIMBAD biblio

We present a complete spectroscopic survey of 2414 2MASS-selected blue horizontal branch (BHB) candidates selected over 4300deg² of the sky. We identify 655 BHB stars in this non-kinematically selected sample. We calculate the luminosity function of field BHB stars, and find evidence for very few hot BHB stars in the field. The BHB stars located at a distance from the Galactic plane|Z| < 4 kpc trace what is clearly a metal-weak thick disk population, with a mean metallicity of [Fe/H] = -1.7, a rotation velocity gradient of dv_rot/d|Z| = -28±3.4 km.s^–1 in the region|Z| < 6 kpc, and a density scale height of h_Z= 1.26±0.1 kpc. The BHB stars located at 5 <|Z| < 9 kpc are a predominantly inner-halo population, with a mean metallicity of [Fe/H] = -2.0 and a mean Galactic rotation of -4±31 km.s^–1. We infer the density of halo and thick disk BHB stars is 104±37 kpc^–3 near the Sun, and the relative normalization of halo to thick-disk BHB stars is 4±1% near the Sun.