The Density Profile and Kinematics of the Milky Way with RR Lyrae Stars
The Density Profile and Kinematics of the Milky Way with RR Lyrae Stars
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DOI：
10.3847/1538-4357/aaac7f
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发表时间：
2018-02
期刊：
影响因子：
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通讯作者：
I. Ablimit;G. Zhao
中科院分区：
文献类型：
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作者：
I. Ablimit;G. Zhao
大多数已知的 RR 天琴座都是 ab 型 RR 天琴座 (RRLab)，它们是绘制银河系及其子结构的绝佳工具。我们发现 Drake 等人确定了 1148 颗 RRLab 恒星。已通过 SDSS 和 LAMOST 的光谱调查观测到。我们在论文 I 中从 860 个晕示踪剂中推导出了径向速度色散、圆周速度和质量分布。这里我们展示了银河系厚盘和晕的恒星密度和径向速度分布。位于厚盘中的 288 颗 RRLab 恒星的平均金属丰度为 [Fe/H] = -1.02。三个厚圆盘示踪剂的径向速度低于 215 km s−1。使用平均金属丰度为 [Fe/H] = −1.33 的 860 个晕示踪剂，我们发现了 n(r) ∝ r−2.8 和 n(r) ∝ r−4.8 的双幂定律，断裂距离为 21 kpc，以表达晕恒星密度剖面。 50 kpc 时的径向速度色散约为 78 km s−1。
Most of the known RR Lyraes are type ab RR Lyraes (RRLab), and they are an excellent tool to map the Milky Way and its substructures. We find that 1148 RRLab stars determined by Drake et al. have been observed by spectroscopic surveys of SDSS and LAMOST. We derived the radial velocity dispersion, circular velocity, and mass profile from 860 halo tracers in Paper I. Here we present the stellar densities and radial velocity distributions of the thick disk and halo of the Milky Way. The 288 RRLab stars located in the thick disk have the mean metallicity of [Fe/H] = −1.02. Three thick disk tracers have a radial velocity lower than 215 km s−1. With 860 halo tracers, which have a mean metallicity of [Fe/H] = −1.33, we find a double power law of n(r) ∝ r−2.8 and n(r) ∝ r−4.8 with a break distance of 21 kpc to express the halo stellar density profile. The radial velocity dispersion at 50 kpc is around 78 km s−1.