标题： 历经沧桑：太阳邻域的运动学和化学组分 显示英文标题

标题： Through Thick and Thin: Kinematic and Chemical Components in the Solar Neighbourhood

摘要： 我们利用已发表的数据搜索太阳邻域中化学性质不同的恒星组分的存在性。 通过扩展早期的工作，我们表明，当考虑铁（Fe）、α元素以及r过程元素Eu的丰度时，恒星可以清晰地分为两组，分别对应银河系的传统薄盘和厚盘。 与薄盘相似的组别由[Fe/H]>-0.7且α/Fe<0.2的恒星所追踪。 厚盘类似的组别在[Fe/H]上与薄盘重叠，但α元素和Eu的丰度更高。 然而，在-1.5<[Fe/H]<-0.7范围内且具有低[α/Fe]比值的恒星似乎属于一个独立的、动力学较冷、非旋转的组分，我们认为这与潮汐碎片有关。 对于[Fe/H]<-1.5，运动学热恒星晕主导样本。 这些结果表明，仅通过化学性质可能定义太阳邻域的主要动力学组分，这种方法具有若干有趣的后果。 薄盘恒星的动力学与金属量无关：它们在-0.7<[Fe/H]<+0.4范围内的平均旋转速度大致保持恒定，这一结果反对径向迁移在薄盘演化中发挥了重要作用的观点。 分配到薄盘的恒星的速度弥散也与[Fe/H]无关，这意味着随着金属量减少而增加的速度弥散是由于较低金属量下厚盘盛行率的增加，而不是动力学加热机制持续运行的结果。 各种组分在[Fe/H]和可能的恒星年龄上的显著重叠可能会影响太阳邻域恒星性质中的其他报告趋势。 显示英文摘要

摘要： We search for the existence of chemically-distinct stellar components in the solar neighbourhood using published data. Extending earlier work, we show that when the abundances of Fe, alpha elements, and the r-process element Eu are considered, stars separate neatly into two groups that delineate the traditional thin and thick disk of the Milky Way. The group akin to the thin disk is traced by stars with [Fe/H]>-0.7 and alpha/Fe<0.2. The thick disk-like group overlaps the thin disk in [Fe/H] but has higher abundances of alpha elements and Eu. Stars in the range -1.5<[Fe/H]<-0.7 with low [alpha/Fe] ratios, however, seem to belong to a separate, dynamically-cold, non-rotating component that we associate with tidal debris. The kinematically-hot stellar halo dominates the sample for [Fe/H]<-1.5. These results suggest that it may be possible to define the main dynamical components of the solar neighbourhood using only their chemistry, an approach with a number of interesting consequences. The kinematics of thin disk stars is then independent of metallicity: their average rotation speed remains roughly constant in the range -0.7<[Fe/H]<+0.4, a result that argues against radial migration having played a substantial role in the evolution of the thin disk. The velocity dispersion of stars assigned to the thin disk is also independent of [Fe/H], implying that the familiar increase in velocity dispersion with decreasing metallicity is the result of the increased prevalence of the thick disk at lower metallicities, rather than of the sustained operation of a dynamical heating mechanism. The substantial overlap in [Fe/H] and, probably, stellar age, of the various components might affect other reported trends in the properties of stars in the solar neighbourhood.