球状星团中Oosterhoff二分法追踪的Milky Way晕的恒星形成历史
Star formation history of the Milky Way halo traced by the Oosterhoff dichotomy among globular clusters
摘要：
在我们最近对多星群范式中奥斯特霍夫二分法的研究中（Jang et al. 2014），我们提出奥斯特霍夫I、II和III群球状星团（GC）中的RR天琴座变星主要分别由第一、第二和第三代恒星（G1、G2和G3）产生。在这里，我们表明，第一次，所观察到的二分法在内部和外部晕GC可以自然地复制时，这些模型扩展到所有的金属丰度制度，同时保持合理的协议，在水平分支类型与[Fe/H]的相关性。为了实现这一点，然而，具体的恒星形成的历史是需要的内部和外部晕。在内晕GC中，恒星形成开始和停止较早，各亚群之间的形成时间尺度相对较短（约0.5 Gyr），而在外晕中，G1的形成延迟约0.8 Gyr，G1和G2之间的时间尺度更长（约1.4 Gyr）。这与银河系晕的双重起源是一致的。尽管在细节上的差异，我们的模型表明，Oosterhoff周期组观察到的外晕和内晕GC的不稳定带内的“人口转移”的影响，其起源可以追溯到两个或三个离散的情节在GC的恒星形成的表现。
英文摘要：
In our recent investigation of the Oosterhoff dichotomy in the multiple population paradigm (Jang et al. 2014), we have suggested that the RR Lyrae variables in the Oosterhoff groups I, II, and III globular clusters (GCs) are produced mostly by the first, second, and third generation stars (G1, G2, and G3), respectively. Here we show, for the first time, that the observed dichotomies in the inner and outer halo GCs can be naturally reproduced when these models are extended to all metallicity regimes, while maintaining reasonable agreements in the horizontal-branch type versus [Fe/H] correlations. In order to achieve this, however, specific star formation histories are required for the inner and outer halos. In the inner halo GCs, the star formation commenced and ceased earlier with relatively short formation timescale between the subpopulations (~0.5 Gyr), while in the outer halo, the formation of G1 was delayed by ~0.8 Gyr with more extended timescale between G1 and G2 (~1.4 Gyr). This is consistent with the dual origin of the Milky Way halo. Despite the difference in detail, our models show that the Oosterhoff period groups observed in both outer and inner halo GCs are all manifestations of the "population-shift" effect within the instability strip, for which the origin can be traced back to the two or three discrete episodes of star formation in GCs.
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。
