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arXiv 1305.2652astro-ph.GA
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星团整体恒星质量函数的演化:解析描述

The evolution of the global stellar mass function of star clusters: an analytic description

Henny J. G. L. M. Lamers, Holger Baumgardt, Mark Gieles

摘要:

通过对不同初始质量和初始浓度的星团在不同潮汐环境中的圆轨道和椭圆轨道上的N体模拟,研究了星团的整体恒星质量函数(MF)的演化.包括有和没有初始质量分离的模型。在最初的罗奇体积(潮汐)填充集群中的低质量恒星的耗尽通常开始于核心坍缩时间的顺序的时间尺度上。在最初未充满其罗奇体积的星系团中,这需要更长的时间,因为在动力学质量损失变得重要之前,星系团必须膨胀到它们的潮汐半径。我们引入了微分质量函数(DMF)的概念,它描述了相对于初始质量函数(IMF)的变化。我们表明,DMF的演变可以描述一组非常简单的解析表达式,适用于广泛的初始集群参数和不同的IMF。这种描述和模型之间的协议是非常好的,除了最初的罗奇体积填充不足的集群,严重的质量隔离。

英文摘要:

The evolution of the global stellar mass function (MF) of star clusters is studied based on a large set of N-body simulations of clusters with a range of initial masses, initial concentrations, in circular or elliptical orbits in different tidal environments. Models with and without initial mass segregation are included. The depletion of low mass stars in initially Roche-volume (tidal) filling clusters starts typically on a time scale of the order of the core collapse time. In clusters that are initially underfilling their Roche-volume it takes longer because the clusters have to expand to their tidal radii before dynamical mass loss becomes important. We introduce the concept of the differential mass function (DMF), which describes the changes with respect to the initial mass function (IMF). We show that the evolution of the DMF can be described by a set of very simple analytic expressions that are valid for a wide range of initial cluster parameters and for different IMFs. The agreement between this description and the models is very good, except for initially Roche-volume underfilling clusters that are severely mass segregated.

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