The Dependence of Fragmentation of Metal-Deficient Gas Clouds on H2 and HD Cooling and the Initial Mass Function of First Generation Stars
The Dependence of Fragmentation of Metal-Deficient Gas Clouds on H2 and HD Cooling and the Initial Mass Function of First Generation Stars
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贫金属气体云破碎对 H2 和 HD 冷却的依赖性以及第一代恒星的初始质量函数
DOI：
10.1143/ptps.147.99
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发表时间：
2002
期刊：
影响因子：
--
通讯作者：
M. Umemura
中科院分区：
文献类型：
--
作者：
F. Nakamura;M. Umemura
近年来的三维数值模拟表明，非线性结构是早期宇宙结构形成的最显著特征之一。星云的碎裂预计将导致第一代恒星的形成。在这种背景下，我们研究了引力坍缩和破碎的对流云轴对称流体动力学模拟与非平衡化学的H2和HD。本文回顾了我们最近的研究结果，并给出了一些补充的数值结果。特别注意了对流云的动力学稳定性和HD冷却的作用，HD冷却在某些星系际环境中比H2冷却更为重要。我们的模拟表明，第一代恒星缺乏亚太阳质量的恒星。根据这些模拟，低质量第一恒星的典型质量应该是1 M O .，大质量第一恒星的典型质量应该在10 2 M O或10 M O左右。这取决于H2的丰度分数，这决定了HD冷却的效率。我们预测恒星IMF是双峰的，在1- 2 MO和10 MO或10 MO处有两个峰。
Recent threee-dimensional numerical simulations have shown that a filamentary structure is one of the most prominent features in the structure formation of the early universe. Fragmentation of the filamentary clouds is expected to lead to the formation of first generation stars. In this context, we have studied the gravitational collapse and fragmentation of filamentary clouds with axisymmetric hydrodynamic simulations coupled with non-equilibrium chemistry of H 2 and HD. In this paper we review our recent results and show some supplemental numerical result Special attention is paid to the dynamical stability of the filamentary clouds and the role of HD cooling which becomes more dominant than H 2 cooling in some intergalactic environments. Our simulations suggest that the first generation stars are deficient in sub-solar mass stars. According to these simulations, a typical mass of low-mass first stars should be of order of 1M O .,and a typical mass of massive first stars should be around 10 2 M O .or 10M O ..depending on the H 2 fractional abundance, which determines the efficiency of HD cooling. We predict that the stellar IMF is bimodal with two peaks at 1- 2M O .and 10M O .or 10M O ..