Bibcode
Brown, Warren R.; Beers, Timothy C.; Wilhelm, Ronald; Allende Prieto, Carlos; Geller, Margaret J.; Kenyon, Scott J.; Kurtz, Michael J.
Referencia bibliográfica
The Astronomical Journal, Volume 135, Issue 2, pp. 564-574 (2008).
Fecha de publicación:
2
2008
Número de citas
47
Número de citas referidas
44
Descripción
We present a complete spectroscopic survey of 2414 2MASS-selected blue
horizontal branch (BHB) candidates selected over 4300 deg2 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 dvrot/d|Z|
= -28 ± 3.4 km s-1 in the region |Z| < 6 kpc, and a
density scale height of hZ = 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.