THE FORMATION OF SECONDARY STELLAR GENERATIONS IN MASSIVE YOUNG STAR CLUSTERS FROM RAPIDLY COOLING SHOCKED STELLAR WINDS
THE FORMATION OF SECONDARY STELLAR GENERATIONS IN MASSIVE YOUNG STAR CLUSTERS FROM RAPIDLY COOLING SHOCKED STELLAR WINDS
复制标题
快速冷却的冲击恒星风在巨大的年轻星团中形成第二代恒星
DOI：
10.3847/1538-4357/835/1/60
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发表时间：
2016
期刊：
影响因子：
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通讯作者：
S. Ehlerová
中科院分区：
文献类型：
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作者：
R. Wünsch;J. Palouš;G. Tenorio;S. Ehlerová
我们研究了一个模型，快速冷却冲击恒星风在年轻的大规模集群和估计的情况下，二次星星形成，从第一代恒星（1G）的重新插入的风，是可能的。我们使用了两种实现的模型：一个高度理想化的，计算成本低，球对称半解析模型，和一个复杂的，三维辐射流体动力学，模拟，他们是在一个很好的相互协议。结果证实了我们之前的发现，在一个1G质量107 M <$，半质量半径2.38 pc的星团中，受冲击的恒星风变得热不稳定，坍缩成致密的气体结构，部分积聚在星团内部，自我屏蔽电离恒星辐射，并形成第二代（2G）恒星。我们使用半解析模型来探索参数空间的一个子集，该子集覆盖了广泛的观测上不受约束的参数：加热效率ηhe和质量负载ηml。结果表明，当ηhe ≥ 10%时，1G星风在星团内的累积比例可大于50%，这与观测结果相符。此外，对于低ηhe，该模型提供了一个自洽的机制，预测2G星只在星团的中心区域形成。最后，我们计算了相互作用星系NGC 4038/9（银河系）中超星星团的H30α复合线的累积暖气体辐射，分析了其速度剖面，并估算了其强度，表明用阿尔马可以探测到暖气体。
We study a model of rapidly cooling shocked stellar winds in young massive clusters and estimate the circumstances under which secondary star formation, out of the reinserted winds from a first stellar generation (1G), is possible. We have used two implementations of the model: a highly idealized, computationally inexpensive, spherically symmetric semi-analytic model, and a complex, three-dimensional radiation-hydrodynamic, simulation; they are in a good mutual agreement. The results confirm our previous findings that, in a cluster with 1G mass 107 M⊙ and half-mass–radius 2.38 pc, the shocked stellar winds become thermally unstable, collapse into dense gaseous structures that partially accumulate inside the cluster, self-shield against ionizing stellar radiation, and form the second generation (2G) of stars. We have used the semi-analytic model to explore a subset of the parameter space covering a wide range of the observationally poorly constrained parameters: the heating efficiency, ηhe, and the mass loading, ηml. The results show that the fraction of the 1G stellar winds accumulating inside the cluster can be larger than 50% if ηhe ≲ 10%, which is suggested by the observations. Furthermore, for low ηhe, the model provides a self-consistent mechanism predicting 2G stars forming only in the central zones of the cluster. Finally, we have calculated the accumulated warm gas emission in the H30α recombination line, analyzed its velocity profile, and estimated its intensity for super star clusters in interacting galaxies NGC4038/9 (Antennae) showing that the warm gas should be detectable with ALMA.