世纪巡天星系晕计划III：对弱金属厚盘和内晕中蓝色水平分支星的4300 deg^2完整巡天
The Century Survey Galactic Halo Project III: A Complete 4300 deg^2 Survey of Blue Horizontal Branch Stars in the Metal-Weak Thick Disk and Inner Halo
摘要：
我们对2414个2 MASS选择的蓝色水平分支（BHB）候选者进行了完整的光谱调查，这些候选者选择了4300度^2的天空。我们确定655 BHB星在这个非运动学选择的样本。我们计算了BHB星的光度函数，并找到了现场很少热BHB星的证据。位于距银道面|Z| <4 kpc距离的BHB星，其轨迹明显是一个金属弱厚盘星群，平均金属丰度为[Fe/H]=-1.7，在|Z| <6 kpc的区域内，自转速度梯度为dv_{rot} /d |Z| = -28+-3.4 km/s，密度标度高度为h_Z= 1.26+-0.1 kpc。位于5< |Z| <9 kpc的BHB星主要是内晕星群，平均金属丰度为[Fe/H]= -2.0，平均银河系自转为-4+-31 km/s。我们推断太阳附近晕和厚盘BHB星的密度为104+-37 kpc^-3，太阳附近晕相对于厚盘BHB星的相对标准化为4+-1%。
英文摘要：
We present a complete spectroscopic survey of 2414 2MASS-selected blue horizontal branch (BHB) candidates selected over 4300 deg^2 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 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. 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.
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