太阳邻域化学标记中6个类群的母体种群
The Parent Populations of 6 groups identified from Chemical Tagging in the Solar neighborhood
摘要：
我们估计了Mitschang等人在化学标记实验中确定的6个最大（太阳附近至少有20颗恒星）化学基团的母体种群的大小和分布。2014.丰度组中的恒星倾向于位于角动量与离心率空间的边界附近，在那里发现恒星的概率最高，并且轨道的远心点近似等于太阳的银河系中心半径。假设母种群均匀分布在银河系的所有方位角上，我们估计这些丰度组的母种群至少包含20万个成员。星群角动量的分布意味着，只有两个最年轻的星群和其中角动量最大的星群，才不符合均匀方位角分布的假设。三个薄盘组的母星群具有窄的角动量分布，但偏心率和角动量分布的尾部表明只有一小部分恒星迁移并增加了偏心率。与此相反，厚盘组的母种群表现出广泛的角动量和偏心率分布，这意味着加热和径向迁移已经发生。
英文摘要：
We estimate the size and distribution of the parent populations for the 6 largest (at least 20 stars in the Solar neighborhood) chemical groups identified in the Chemical Tagging experiment by Mitschang et al.~2014. Stars in the abundance groups tend to lie near a boundary in angular momentum versus eccentricity space where the probability is highest for a star to be found in the Solar neighborhood and where orbits have apocenter approximately equal to the Sun's galactocentric radius. Assuming that the parent populations are uniformly distributed at all azimuthal angles in the Galaxy, we estimate that the parent populations of these abundance groups contain at least 200,000 members. The spread in angular momentum of the groups implies that the assumption of a uniform azimuthal distribution only fails for the two youngest groups and only for the highest angular momentum stars in them. The parent populations of three thin disk groups have narrow angular momentum distributions, but tails in the eccentricity and angular momentum distributions suggest that only a small fraction of stars have migrated and increased in eccentricity. In contrast, the parent populations of the thick disk groups exhibit both wide angular momentum and eccentricity distributions implying that both heating and radial migration has taken place.
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