Evidence for Primordial Mass Segregation in Globular Clusters
Evidence for Primordial Mass Segregation in Globular Clusters
复制标题
球状星团中原初质量偏析的证据
DOI：
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发表时间：
2008
期刊：
影响因子：
--
通讯作者：
P. Kroupa
中科院分区：
文献类型：
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作者：
H. Baumgardt;G. de Marchi;P. Kroupa
利用Aarseth的N体碰撞程序NBODY4，在GRAPE6专用计算机上，研究了初始质量分离星团和未分离星团在外潮场下由于两体弛豫而发生的溶解。当把最初非质量分离模型的结果外推到球状星团时，我们得到了毁灭前的时间和质量函数的斜率之间的关联，在这个意义上，更接近于溶解的球状星团在低质量恒星中被更强烈地耗尽。这种关联符合观测到的大多数球状星团的质量函数。然而，在低质量恒星中，几个球状星团的质量函数比这些模型所建议的更强烈地耗尽。如果球状星团最初开始质量分离，就可以解释这种强烈耗尽的质量函数。原始质量分离也解释了恒星质量函数的斜率与De Marchi及其同事最近发现的星团浓度之间的关联。在这种情况下，所有球状星团都有可能以类似于当今宇宙中年轻疏散星团的质量函数开始，至少对于m=0.8M☉以下的恒星是这样。这证明了在-2<；[Fe/H]<；0范围内，质量函数对于不同的恒星形成环境和金属丰度具有近乎普适性。最后，我们描述了一种新的算法，该算法可以初始化具有任意密度分布和质量分离量的静止质量分离星团。
We have studied the dissolution of initially mass-segregated and unsegregated star clusters due to two-body relaxation in external tidal fields, using Aarseth’s collisional N-body code NBODY4 on GRAPE6 special-purpose computers. When extrapolating results of initially non-mass-segregated models to globular clusters, we obtain a correlation between the time until destruction and the slope of the mass function, in the sense that globular clusters that are closer to dissolution are more strongly depleted in low-mass stars. This correlation fits observed mass functions of most globular clusters. The mass functions of several globular clusters are, however, more strongly depleted in low-mass stars than is suggested by these models. Such strongly depleted mass functions can be explained if globular clusters started initially mass segregated. Primordial mass segregation also explains the correlation between the slope of the stellar mass function and the cluster concentration that was recently discovered by De Marchi and coworkers. In this case, it is possible that all globular clusters started with a mass function similar to that seen in young open clusters in the present-day universe, at least for stars below m = 0.8 M☉. This argues for a near universality of the mass function for different star formation environments and metallicities in the range -2 < [ Fe/H ] < 0. We finally describe a novel algorithm that can initialize stationary mass-segregated clusters with an arbitrary density profile and amount of mass segregation.
一种在维里平衡中创建初始质量分离星团的新方法
DOI：
10.1111/j.1365-2966.2008.12993.x
发表时间：
2008
影响因子：
4.8
作者：
Kroupa;Baumgardt
通讯作者：
Baumgardt