论文标题
银河盘的证据rr〜lyrae星星在太阳能街区
Evidence for Galactic disc RR~Lyrae stars in the Solar neighbourhood
论文作者
论文摘要
我们使用公共可用的光度法，光谱和{\ it Gaia} DR2星形数据进行了对太阳邻域314 rr〜lyrae恒星的运动学研究，以以银河系的方式探索它们的分布。我们报告在太阳街区的过度密度为22 rr〜lyrae恒星，距离银河中心的kpc之间的周围距离为5--9 \。它们的轨道参数及其化学反应表明，这22个变量共享银河盘的运动学和[Fe/H]值，其平均金属性和切线速度为[Fe/H] = $ -0.60 $ \，DEX和$V_θ和$v_θ= 241 $ \，km \，km \，km \，s $ $^$ 1} $} $} $^{-1} $} $} $^{-1} $} $} $^{-1} $} n}从半乳突的球形速度组件的分布中，我们发现这22个类似盘的Rr〜lyrae变量与{\ it gaia} sausage（{\ it gaia} -enceladus）不一致，与本地Rr〜lyrae恒星的几乎一半不同。文献中的化学信息表明，大多数选定的折峰峰rr〜lyrae变量为$α$ - 贫困，这是薄盘中通常很年轻的恒星所共有的属性。使用可用的光度法，我们排除可能与已知的经典和异常的头孢虫进行错误分类。这些椎间盘rr〜lyrae恒星的类似运动学，化学和脉动特性表明它们具有共同的起源。相比之下，我们发现与{\ it gaia} -enceladus相关的rr〜lyrae恒星基于它们的运动学和化学成分，表明在旧人群中散布了相当大的金属性（$ \ sim $ 〜1 \ 1 \，dex）。
We present a kinematical study of 314 RR~Lyrae stars in the solar neighbourhood using the publicly available photometric, spectroscopic, and {\it Gaia} DR2 astrometric data to explore their distribution in the Milky Way. We report an overdensity of 22 RR~Lyrae stars in the solar neighbourhood at a pericenter distance of between 5--9\,kpc from the Galactic center. Their orbital parameters and their chemistry indicate that these 22 variables share the kinematics and the [Fe/H] values of the Galactic disc, with an average metallicity and tangential velocity of [Fe/H]=$-0.60$\,dex and $v_θ = 241$\,km\,s$^{-1}$, respectively. From the distribution of the Galactocentric spherical velocity components, we find that these 22 disc-like RR~Lyrae variables are not consistent with the {\it Gaia} Sausage ({\it Gaia}-Enceladus), unlike almost half of the local RR~Lyrae stars. Chemical information from the literature shows that the majority of the selected pericenter peak RR~Lyrae variables are $α$-poor, a property shared by typically much younger stars in the thin disc. Using the available photometry we rule out a possible misclassification with the known classical and anomalous Cepheids. The similar kinematic, chemical, and pulsation properties of these disc RR~Lyrae stars suggest they share a common origin. In contrast, we find the RR~Lyrae stars associated with the {\it Gaia}-Enceladus based on their kinematics and chemical composition show a considerable metallicity spread in the old population ($\sim$~1\,dex).
