The Formation of Stellar Clusters in Turbulent Molecular Clouds: Effects of the Equation of State
The Formation of Stellar Clusters in Turbulent Molecular Clouds: Effects of the Equation of State
复制标题
湍流分子云中恒星团的形成：状态方程的影响
DOI：
10.1086/375780
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发表时间：
2002
期刊：
影响因子：
--
通讯作者：
M. Mac Low
中科院分区：
文献类型：
--
作者：
Yue;R. Klessen;M. Mac Low
我们用三维光滑粒子流体力学模拟研究了在湍流分子云中改变状态方程对星团形成的影响。我们的结果表明，状态方程有助于确定自引力气体碎片的强度。碎裂程度随着多变指数γ的增加而降低，在0.2；γ和1.4范围内，尽管附着在坍塌碎片上的总质量似乎在该范围内大致保持不变。较低的γ值预计会导致低质量恒星的密集星团的形成，而γ>；1可能会导致孤立的大质量恒星的形成。正如分析论证所预期的那样，γ>；1.4中的碎片化和崩溃完全停止了。对于非自引力湍流气体，过密气团的质量谱大致为对数正态分布，但在重力的作用下变化为幂定律。另一方面，对于γ≤1，坍塌岩心的谱保持对数正态分布，而对于γ>；1，则显著变平。密度概率函数接近对数正态分布，宽度随着γ的增加而减小。原始气体可能有有效的γ>；1，在这种情况下，这些结果可以帮助解释为什么第一批恒星形成的模型倾向于产生孤立的大质量天体。
We study the effect of varying the equation of state on the formation of stellar clusters in turbulent molecular clouds using three-dimensional, smoothed particle hydrodynamics simulations. Our results show that the equation of state helps determine how strongly self-gravitating gas fragments. The degree of fragmentation decreases with increasing polytropic exponent γ in the range 0.2 < γ < 1.4, although the total amount of mass accreted onto collapsed fragments appears to remain roughly constant through that range. Low values of γ are expected to lead to the formation of dense clusters of low-mass stars, while γ > 1 probably results in the formation of isolated and massive stars. Fragmentation and collapse ceases entirely for γ > 1.4, as expected from analytic arguments. The mass spectrum of overdense gas clumps is roughly lognormal for non-self-gravitating turbulent gas, but changes to a power law under the action of gravity. The spectrum of collapsed cores, on the other hand, remains lognormal for γ ≤ 1 but flattens markedly for γ > 1. The density probability function approaches lognormal, with widths that decrease with increasing γ. Primordial gas may have effective γ > 1, in which case these results could help explain why models of the formation of the first stars tend to produce isolated, massive objects.
影响因子：
3.2
作者：
V. Mannings;A. Boss;S. Russell
通讯作者：
V. Mannings;A. Boss;S. Russell