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arXiv 0806.1460astro-ph
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星系团核心的早期扩张

The Early Expansion of Cluster Cores

N. Bastian, M. Gieles, S. P. Goodwin, G. Trancho, L. J. Smith, I. Konstantopoulos, Yu. Efremov

摘要:

观测到的年轻星团的性质,如核心半径和光度分布,在星团的早期演化过程中迅速变化。在这里,我们提出了6个年轻的星团在M51的观测,我们得出他们的大小使用HST成像和年龄使用深双子北光谱。我们发现的证据表明,在第一个20万年的演化集群核心的快速扩张。我们证实了这一趋势,包括银河系和银河系外的嵌入式和年轻的集群的文献中的数据,并讨论了可能的机制(快速气体去除,恒星演化质量损失,和内部动力学加热)。我们探讨了这一结果的影响,集中在一个事实,即集群更集中在过去,这意味着他们的恒星密度要高得多,弛豫时间相应地较短。因此,当估计特定簇是否动态弛豫时(即,当确定簇的质量分离是由于原始过程还是动态过程时),当前弛豫时间仅是上限,其中弛豫时间在过去可能显著更短。

英文摘要:

The observed properties of young star clusters, such as the core radius and luminosity profile, change rapidly during the early evolution of the clusters. Here we present observations of 6 young clusters in M51 where we derive their sizes using HST imaging and ages using deep Gemini-North spectroscopy. We find evidence for a rapid expansion of the cluster cores during the first 20 Myr of their evolution. We confirm this trend by including data from the literature of both Galactic and extra-galactic embedded and young clusters, and possible mechanisms (rapid gas removal, stellar evolutionary mass-loss, and internal dynamical heating) are discussed. We explore the implications of this result, focussing on the fact that clusters were more concentrated in the past, implying that their stellar densities were much higher and relaxation times correspondingly shorter. Thus, when estimating if a particular cluster is dynamically relaxed, (i.e. when determining if a cluster's mass segregation is due to primordial or dynamical processes), the current relaxation time is only an upper-limit, with the relaxation time likely being significantly shorter in the past.

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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