论文标题
RR Lyrae星的运动学在银河凸起中带有Ogle-IV和Gaia Dr2
Kinematics of RR Lyrae stars in the Galactic bulge with OGLE-IV and Gaia DR2
论文作者
论文摘要
我们通过结合Ogle-IV光度数据和GAIA DR2适当的运动来分析银河系凸起的15,599个基本模式RR Lyre（RRL）恒星的运动学和空间分布。我们表明，纵向适当的运动和视线速度可以为银河中央区域的旋转带来相似的结果。发现凸起的rrls的角速度约为$ 35 $ km s $^{ - 1} $ kpc $^{ - 1} $，大得多，大得多的恒星（$ 50-60 $ km s $ s $^{ - 1} $^{ - 1} $ kpc $ kpc $^{ - 1} $^{ - 1} $）; Bulge RRL的速度分散剂（120 $ - $ 140 km s $^{ - 1} $）比年轻的星星。凸起RRL的运动学对金属性的依赖性通过其旋转曲线和空间分布显示。金属贫困的RRL（[Fe/H] <$ -1 $）显示出比金属富含金属的杆角度。我们还发现线索表明，凸起中的RRL不受光环恒星的主导。这些结果可能解释了对凸起的RRL的一些冲突结果，并有助于了解银河凸出的化学动力学演化。
We analyze the kinematics and spatial distribution of 15,599 fundamental-mode RR Lyrae (RRL) stars in the Milky Way bulge by combining OGLE-IV photometric data and Gaia DR2 proper motions. We show that the longitudinal proper motions and the line-of-sight velocities can give similar results for the rotation in the Galactic central regions. The angular velocity of bulge RRLs is found to be around $35$ km s$^{-1}$ kpc$^{-1}$, significantly smaller than that for the majority of bulge stars ($50-60$ km s$^{-1}$ kpc$^{-1}$); bulge RRLs have larger velocity dispersion (120$-$140 km s$^{-1}$) than younger stars. The dependence of the kinematics of the bulge RRLs on their metallicities is shown by their rotation curves and spatial distributions. Metal-poor RRLs ([Fe/H]<$-1$) show a smaller bar angle than metal-rich ones. We also find clues suggesting that RRLs in the bulge are not dominated by halo stars. These results might explain some previous conflicting results over bulge RRLs and help understand the chemodynamical evolution of the Galactic bulge.
