Dynamical ejections of massive stars from young star clusters under diverse initial conditions
Dynamical ejections of massive stars from young star clusters under diverse initial conditions
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不同初始条件下年轻星团中大质量恒星的动态喷射
DOI：
10.1051/0004-6361/201628233
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发表时间：
2016
期刊：
影响因子：
--
通讯作者：
Kroupa
中科院分区：
文献类型：
--
作者：
Kroupa
我们研究了星星团的初始条件和大质量星星的人口对大质量恒星从星星团中的动力学抛射的影响。我们使用一个大的直接N体计算中等质量星星（Mecl <$103.5 M <$）。我们改变了计算的初始条件，如初始的半质量半径的集群，初始的大质量恒星和初始质量分离的双星种群。我们发现，初始密度是最有影响力的质量系统的喷射分数的参数。初始半质量半径rh（0）为0.1（0.3）pc的星系团平均可以喷射出50%（30）的O星系统，而初始较大的（rh（0）= 0.8 pc）星系团，即密度较低的星系团，几乎不喷射出任何OB星（最多约4.5%）。当双星由两颗质量相近的恒星组成时，抛射作用最为有效。大多数模型表明，平均射血分数随恒星质量的减小而减小。对于有效地喷射O星的星团，被喷射的恒星的质量函数与给定的初始质量函数（IMF）相比是头重脚轻的，而留在星团中的恒星的质量函数变得比IMF稍微陡峭（顶轻）。在我们的N体模型中，300万年老星团中恒星的顶轻质量函数与先前报道的M31中年轻中等质量星团的平均质量函数吻合得很好。这意味着观测到的年轻团簇的IMF是正则IMF。我们发现，弹射出的大质量恒星的多重性分数可以高达10.60%，大规模的高阶多重系统可以动态地弹射出，并且高阶多重变得常见，特别是在集群中。我们还讨论了喷出的大质量系统的二进制人口。最初没有质量分离的星团在质量分离引起的时间延迟后开始喷射大质量恒星。当一个大规模的运动学调查的大质量场星成为可用的，例如通过盖亚，我们的结果可能会被用来限制出生配置的大质量恒星的星星集群。然而，这里给出的结果已经表明，对于质量比q ≥ 0.1，O型恒星的初生质量比分布必须接近均匀。
We study the effects that initial conditions of star clusters and their massive star population have on dynamical ejections of massive stars from star clusters up to an age of 3 Myr. We use a large set of directN-body calculations for moderately massive star clusters (Mecl≈ 103.5M⊙). We vary the initial conditions of the calculations, such as the initial half-mass radius of the clusters, initial binary populations for massive stars and initial mass segregation. We find that the initial density is the most influential parameter for the ejection fraction of the massive systems. The clusters with an initial half-mass radiusrh(0) of 0.1 (0.3) pc can eject up to 50% (30)% of their O-star systems on average, while initially larger (rh(0) = 0.8 pc) clusters, that is, lower density clusters, eject hardly any OB stars (at most ≈ 4.5%). When the binaries are composed of two stars of similar mass, the ejections are most effective. Most of the models show that the average ejection fraction decreases with decreasing stellar mass. For clusters that are efficient at ejecting O stars, the mass function of the ejected stars is top-heavy compared to the given initial mass function (IMF), while the mass function of stars that remain in the cluster becomes slightly steeper (top-light) than the IMF. The top-light mass functions of stars in 3 Myr old clusters in ourN-body models agree well with the mean mass function of young intermediate-mass clusters in M 31, as reported previously. This implies that the IMF of the observed young clusters is the canonical IMF. We show that the multiplicity fraction of the ejected massive stars can be as high as ≈ 60%, that massive high-order multiple systems can be dynamically ejected, and that high-order multiples become common especially in the cluster. We also discuss binary populations of the ejected massive systems. Clusters that are initially not mass-segregated begin ejecting massive stars after a time delay that is caused by mass segregation. When a large kinematic survey of massive field stars becomes available, for instance throughGaia, our results may be used to constrain the birth configuration of massive stars in star clusters. The results presented here, however, already show that the birth mass-ratio distribution for O-star primaries must be near uniform for mass ratiosq≳ 0.1.
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DOI：
10.1111/j.1365-2966.2012.20767.x
发表时间：
2012-02
影响因子：
4.8
作者：
M. Marks;P. Kroupa;J. Dabringhausen;M. Pawlowski
通讯作者：
M. Marks;P. Kroupa;J. Dabringhausen;M. Pawlowski
DOI：
10.1088/0004-637x/746/1/15
发表时间：
2011-11
期刊：
The Astrophysical Journal
影响因子：
--
作者：
S. Banerjee;P. Kroupa;Seungkyung Oh
通讯作者：
S. Banerjee;P. Kroupa;Seungkyung Oh
银河系中心大质量场恒星的起源：光谱研究
DOI：
10.1093/mnras/stu2116
发表时间：
2014
期刊：
arXiv: Astrophysics of Galaxies
影响因子：
--
作者：
Hui Dong;J. Mauerhan;M. Morris;Q. Wang;A. Cotera
通讯作者：
A. Cotera
星团 N 体计算中双星轨道参数分布演化的分析描述
DOI：
10.1111/j.1365-2966.2011.19257.x
发表时间：
2011
影响因子：
4.8
作者：
M. Marks;P. Kroupa;Seungkyung Oh
通讯作者：
Seungkyung Oh
DOI：
--
发表时间：
2008
期刊：
影响因子：
--
作者：
H. Baumgardt;G. de Marchi;P. Kroupa
通讯作者：
P. Kroupa