论文标题
关于太阳能社区中金属贫困星的起源
On the Origin of Metal-poor Stars in the Solar Neighborhood
论文作者
论文摘要
我们确定了六个金属贫困（-2.4 <[fe/h] <-1 dex）F型高运动（HPM）恒星的年龄，运动学参数和银河轨道参数（-2.4 <[fe/h] <-1 dex），以研究其HPM性质和起源。对于运动学过程，使用了GAIA DR2的星体数据。六个小矮人的高分辨率Elodie光谱也用于获得准确的[fe/h]丰度和最新的[$α$/fe]丰度。恒星年龄的计算基于贝叶斯统计，计算的年龄在9.5-10.1 Gyrs范围内。根据金属性和年龄，六个HMP星星是Halo（HD6755，HD84937，BD +42 3607）的成员，或厚磁盘的低金属尾巴（HD 3567，HD 194598，HD 2018，HD 201891）的成员。但是，银河轨道参数表明薄磁盘（HD 84937，HD 194598），厚磁盘（HD 3567，HD 201891）和Halo（HD 6755，BD +42 3607）种群。还针对候选GC的逃生方案进行了动力分析。矮星系的潮汐破坏也被认为是另一种起源。 HD 6755，HD 194598和HD 3567带有逆行轨道运动的HD 3567可能是潮汐破坏矮星系的候选恒星。但是，HD 194598与NGC 6284的关系提出了一个有趣的案例。它的相遇速度较低（16 +/- 28 km/s），它们的年龄和金属性在1 $σ$水平上几乎是一致的。其余的HPM样品恒星具有1.5潮汐半径与选定的GC相遇的4％至18％的概率。这表明程序恒星的球状簇起源不太可能。
We determined the ages, the kinematic parameters and Galactic orbital parameters of six metal-poor (-2.4<[Fe/H]<-1 dex) F-type high proper motion (HPM) stars to investigate their HPM nature and origin. For the kinematical procedure, the astrometric data from the Gaia DR2 was used. High resolution ELODIE spectra of the six dwarfs were also used to obtain accurate [Fe/H] abundances and up-to-date [$α$/Fe] abundances. The calculations for stellar ages were based on Bayesian statistics, with the computed ages falling in the range 9.5-10.1 Gyrs. On the basis of the metallicities and ages, six HMP stars are members of halo (HD6755, HD84937, BD +42 3607) or members of the low-metallicity tail of the thick disk (HD 3567, HD 194598, HD 201891). However, Galactic orbital parameters suggest thin disk (HD 84937, HD 194598), thick disk (HD 3567, HD 201891), and halo (HD 6755, BD +42 3607) population. The dynamical analysis was also performed for the escape scenario from the candidate GCs. The tidal disruption of a dwarf galaxy was also considered to be as an alternative origin. HD 6755, HD 194598, and HD 3567 with their retrograde orbital motions are likely candidate stars for a tidally disrupted dwarf galaxy origin. However, HD 194598 relationship with NGC 6284 presents an interesting case. Its encounter velocity is low (16+/-28 km/s) and their ages and metallicities are very nearly consistent with each other at the 1$σ$ level. The rest of the HPM sample stars have a 4% to 18% probability of encountering with selected GCs for 1.5 tidal radii. This indicates that a globular cluster origin for the program stars is unlikely.
