The Role of Shock Heating in the Evolution of Massive Primordial Clouds
The Role of Shock Heating in the Evolution of Massive Primordial Clouds
复制标题
冲击加热在巨大原始云演化中的作用
DOI：
10.1143/ptps.147.43
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发表时间：
2002
期刊：
影响因子：
--
通讯作者：
M. Yamada
中科院分区：
文献类型：
--
作者：
M. Yamada
研究了激波在块状原始气体云演化中的作用。由于激波加热和随后的非平衡冷却，云中电离度的增加导致了氢分子的形成，氢分子是无金属气体中最重要的冷却剂。在本章中，我们详细地回顾了不同马赫数和前激波密度的激波的影响，并讨论了它们如何影响母云的后续演化。通过不同时间尺度的比较，我们发现，尽管整个系统经历了非平衡演化，但原始气体的化学演化和热演化是相当简单的。这一结果在一个简单的图表(。激波图)，极大地帮助我们解释和预测原始气体云的热演化。最后，我们考虑了碎裂过程本身，并研究了冷却不稳定性可以产生比通过Jeans不稳定性形成的小得多的云团的可能性。
The role of shock waves in the evolution of massive primordial gas clouds is investigated. The increase of the ionization degree in the cloud due to the shock heating, and subsequent non-equilibrium cooling causes the formation of hydrogen molecules, which are the most important coolant in the metal-free gas In this chapter we review the effect of shock waves with various Mach numbers and pre-shock densities in detail and discuss how they affect the following evolution of the parent cloud. By comparison of various timcscales, we show that the chemical evolution and the thermal evolution of the primordial gas are quite simple, in spite of the fact that the system as a whole undergoes non-equilibrium evolution. This result, which is demonstrated in a simple diagram (the . "shock diagram"), greatly helps us to interpret and predict the thermal evolution of the primordial gas clouds. Finally, we consider the fragmentation process itself, and we investigate the possibility that the cooling instability can create much smaller cloudlets than can be formed through the Jeans instability.