论文标题
银河球状簇的哈勃太空望远镜紫外线遗产调查。 xxi。多个恒星种群中的二进制
The Hubble Space Telescope UV Legacy Survey of Galactic Globular Clusters. XXI. Binaries among multiple stellar populations
论文作者
论文摘要
在球状簇(GC)中形成多个种群的许多场景都预测,第二代(2G)恒星以紧凑而密集的子系统形成,嵌入了更扩展的第一代(1G)系统中。如果这些情况是准确的,那么浓密的2G形成环境的结果是,2G二进制组应受到恒星相互作用的影响,并以比1G二进制文件更大的速率破坏。因此,二进制恒星的分数和特性可以提供多个群体GC的形成时期的动力学指纹及其随后的动力学演化。我们研究了五个GC中的二进制文件与多个种群之间的联系,NGC 288,NGC 6121(M 4),NGC 6352,NGC 6362和NGC 6838(M 71)。为此,我们基于F275W,F336W,F438W,F606W和F814W过滤器中的二进制文件的哈勃太空望远镜观测的比较引入了一种新方法。在我们数据探测的内部区域中,我们没有发现四个研究簇中的局部1G和2G二进制发生率之间的巨大差异,唯一的例外是M 4,其中1G二元发射率比2G发生率大三倍。发现的结果与模拟的结果一般一致,这些模拟预测了整体1G和2G事件的显着差异以及集群外部区域中的局部值,但内部区域的发生率相似。在M 4中发现的显着差异与模拟较大的二进制文件较大的模拟一致。我们的分析还提供了混合(1G-2G)二进制物的第一个证据,这是数值模拟预测的人群,是由于出色的相遇而在群集的内部区域形成的,在此期间,二进制的一个组成部分被不同人群的星星代替。
A number of scenarios for the formation of multiple populations in globular clusters (GCs) predict that second generation (2G) stars form in a compact and dense subsystem embedded in a more extended first-generation (1G) system. If these scenarios are accurate, a consequence of the denser 2G formation environment is that 2G binaries should be more significantly affected by stellar interactions and disrupted at a larger rate than 1G binaries. The fractions and properties of binary stars can thus provide a dynamical fingerprint of the formation epoch of multiple-population GCs and their subsequent dynamical evolution. We investigate the connection between binaries and multiple populations in five GCs, NGC 288, NGC 6121 (M 4), NGC 6352, NGC 6362, and NGC 6838 (M 71). To do this, we introduce a new method based on the comparison of Hubble Space Telescope observations of binaries in the F275W, F336W, F438W, F606W and F814W filters with a large number of simulated binaries. In the inner regions probed by our data we do not find large differences between the local 1G and the 2G binary incidences in four of the studied clusters, the only exception being M 4 where the 1G binary incidence is about three times larger than the 2G incidence. The results found are in general agreement with the results of simulations predicting significant differences in the global 1G and 2G incidences and in the local values in the clusters' outer regions but similar incidences in the inner regions. The significant difference found in M 4 is consistent with simulations with a larger fraction of wider binaries. Our analysis also provides the first evidence of mixed (1G-2G) binaries, a population predicted by numerical simulations to form in a cluster's inner regions as a result of stellar encounters during which one component of a binary is replaced by a star of a different population.