RUNAWAY MASSIVE STARS FROM R136: VFTS 682 IS VERY LIKELY A “SLOW RUNAWAY”
RUNAWAY MASSIVE STARS FROM R136: VFTS 682 IS VERY LIKELY A “SLOW RUNAWAY”
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DOI：
10.1088/0004-637x/746/1/15
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发表时间：
2011-11
期刊：
影响因子：
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通讯作者：
S. Banerjee;P. Kroupa;Seungkyung Oh
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作者：
S. Banerjee;P. Kroupa;Seungkyung Oh
本文对大麦哲伦星云剑鱼座30复合体中的大质量星暴星团R136中逃逸大质量恒星的抛射进行了理论研究。具体来说，我们调查了超大质量星星（VMS）VFTS 682是R136失控成员的可能性。最近对上述VMS的观测，凭借其孤立的位置和温和的特殊运动，提出了一个基本问题，即孤立的大质量星星是否确实可能形成。我们执行的第一个现实的N体计算的完全质量分离的R136型星星集群中，所有的大质量恒星在原始的二元系统。这些计算证实，从一个R136-like集群的VMS的动力学弹射，与运动学性质类似的VFTS 682，是常见的。因此，孤立的大质量星星形成的猜想是不必要的，以说明这个VMS。我们的结果也与30 Dor 016的抛射相当一致，这是另一个疑似从R136逃逸的VMS。我们进一步注意到，在星团的演化过程中，大质量双星的合并产生了一些质量明显超过150 M的标准上限的恒星。因此，对R136中这类单颗超正则星的观测并不意味着初始质量函数的上限大大超过了最近提出的正则150 M的上限，它们与正则上限是一致的。
We conduct a theoretical study on the ejection of runaway massive stars from R136—the central massive, starburst cluster in the 30 Doradus complex of the Large Magellanic Cloud. Specifically, we investigate the possibility of the very massive star (VMS) VFTS 682 being a runaway member of R136. Recent observations of the above VMS, by virtue of its isolated location and its moderate peculiar motion, have raised the fundamental question of whether isolated massive star formation is indeed possible. We perform the first realistic N-body computations of fully mass-segregated R136-type star clusters in which all the massive stars are in primordial binary systems. These calculations confirm that the dynamical ejection of a VMS from an R136-like cluster, with kinematic properties similar to those of VFTS 682, is common. Hence, the conjecture of isolated massive star formation is unnecessary to account for this VMS. Our results are also quite consistent with the ejection of 30 Dor 016, another suspected runaway VMS from R136. We further note that during the clusters’ evolution, mergers of massive binaries produce a few single stars per cluster with masses significantly exceeding the canonical upper limit of 150 M☉. The observations of such single super-canonical stars in R136, therefore, do not imply an initial mass function with an upper limit greatly exceeding the accepted canonical 150 M☉ limit, as has been suggested recently, and they are consistent with the canonical upper limit.