Star Formation Patterns and Hierarchies
Star Formation Patterns and Hierarchies
复制标题
恒星形成模式和层次结构
DOI：
10.1051/eas/1151003
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发表时间：
2011
期刊：
影响因子：
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通讯作者：
B. Elmegreen
中科院分区：
文献类型：
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作者：
B. Elmegreen
恒星的形成在空间和时间上都是层次分明的。星系在星际Jeans长度的尺度上形成大区域，这些大区域显然按照大小和密度递减的顺序碎裂成巨大的分子云和云核。年轻恒星遵循这种模式，在最大尺度上产生恒星复合体，在较小尺度上产生OB关联，以此类推，一直到星团和单个恒星。在每个尺度内，在该尺度上的云的生命周期内，较小的区域在时间层次中来来去去。因此，集群的位置与幂函数相关，它们的年龄也是如此。在层次结构的最低级别，观察到成对形成的星团。对于任何这样的层次结构，效率在最密集的区域自动最高。这种高效率促进了束缚团簇的形成。同样，对于任何层次，组件的质量函数是一个幂定律，斜率约为−2，就像观察到的团簇一样。
Star formation occurs in hierarchical patterns in both space and time. Galaxies form large regions on the scale of the interstellar Jeans length and these large regions apparently fragment into giant molecular clouds and cloud cores in a sequence of decreasing size and increasing density. Young stars follow this pattern, producing star complexes on the largest scales, OB associations on smaller scales, and so on down to star clusters and individual stars. Inside each scale and during the lifetime of the cloud on that scale, smaller regions come and go in a hierarchy of time. As a result, cluster positions are correlated with power law functions, and so are their ages. At the lowest level in the hierarchy, clusters are observed to form in pairs. For any hierarchy like this, the efficiency is automatically highest in the densest regions. This high efficiency promotes bound cluster formation. Also for any hierarchy, the mass function of the components is a power law with a slope of around − 2, as observed for clusters.