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arXiv 1909.02767astro-ph.GA
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通过运动学和光谱学程序分析我们银河系的盘成分

Analysis of the disc components of our Galaxy via kinematic and spectroscopic procedures

S. Karaali, S. Bilir, E. Yaz Gokce, O. Plevne

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16 pages, including 15 figures and 5 tables, accepted for publication in PASA
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摘要：

我们使用的光谱和天体测量数据提供的GALAH DR 2和盖亚DR 2，分别为一个大样本的恒星调查的行为[ $α$ /Fe]丰度通过两个程序，即运动学和光谱。利用运动学方法，我们研究了[ $α$ /Fe]丰度在高/低概率薄盘和高/低概率厚盘中的分布，包括总空间速度、[Fe/H]丰度和年龄。高概率薄盘星在[ $α$ /Fe]的所有子区间中占主导地位，包括富星：[ $α$ /Fe] $>0.3$ dex，预计高概率厚盘星将占主导地位。这一结果可以用银河系DR 2的极限视星等（$V<14$等）和恒星样本的中间银河纬度来解释。这四个星群中的恒星共享相等的[ $α$ /Fe]和[Fe/H]丰度、总空间速度和年龄。因此，这些参数中没有一个可以单独用于将恒星样本分成不同的种群。假设丰度为$-1.3<{\rm[Fe/H]}\leq -0.5$ dex、年龄为$9<τ\leq13$ Gyr的高概率薄盘星相对于富金属和年轻的薄盘星具有不同的诞生地。利用光谱学方法，我们根据样品星的年龄和[ $α$ /Fe]和[Fe/H]丰度，将样品星分为富$α$和贫$α$两类。年龄大于8 Gyr的恒星[ $α$ /Fe]比年轻恒星更丰富。我们可以估计丰度[ $α$ /Fe]=0.14 dex作为在[ $α$ /Fe] $\times$ [Fe/H]平面中分离富$α$和贫$α$子样品的边界。

英文摘要：

We used the spectroscopic and astrometric data provided from the GALAH DR2 and Gaia DR2, respectively, for a large sample of stars to investigate the behaviour of the [$α$/Fe] abundances via two procedures, i.e. kinematically and spectroscopically. With the kinematical procedure, we investigated the distribution of the [$α$/Fe] abundances into the high/low probability thin disc, and high/low probability thick-disc populations in terms of total space velocity, [Fe/H] abundance, and age. The high probability thin-disc stars dominate in all sub-intervals of [$α$/Fe], including the rich ones: [$α$/Fe]$>0.3$ dex, where the high probability thick-disc stars are expected to dominate. This result can be explained by the limiting apparent magnitude of the GALAH DR2 ($V<14$ mag) and intermediate Galactic latitude of the star sample. Stars in the four populations share equivalent [$α$/Fe] and [Fe/H] abundances, total space velocities and ages. Hence, none of these parameters can be used alone for separation of a sample of stars into different populations. High probability thin-disc stars with abundance $-1.3<{\rm[Fe/H]}\leq -0.5$ dex and age $9<τ\leq13$ Gyr are assumed to have different birth places relative to the metal rich and younger ones. With the spectroscopic procedure, we separated the sample stars into $α$-rich and $α$-poor categories by means of their ages as well as their [$α$/Fe] and [Fe/H] abundances. Stars older than 8 Gyr are richer in [$α$/Fe] than the younger ones. We could estimate the abundance [$α$/Fe]=0.14 dex as the boundery separating the $α$-rich and $α$-poor sub-samples in the [$α$/Fe]$\times$[Fe/H] plane.

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

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