arXivDaily arXiv每日学术速递 周一至周五更新
arXiv周末暂无论文更新,休息一下吧,周末愉快~~
arXiv 1101.4891astro-ph.GA
收藏

尘埃冷却对低金属量恒星形成云的影响

The effect of dust cooling on low-metallicity star-forming clouds

Gustavo Dopcke, Simon C. O. Glover, Paul C. Clark, Ralf S. Klessen

摘要:

第一个星族的形成理论(Pop III)预测IMF主要由高质量恒星组成,与现今的IMF形成对比,它倾向于产生质量小于1 M_Solar的恒星。特征恒星质量转变的主要理论预测,原因是金属丰度增加提供的额外冷却,特别是尘埃在高密度下提供的冷却。这项工作的目的是测试粉尘冷却是否会导致碎片化,并负责这种转变。为了研究这一点,我们利用高分辨率的流体动力学模拟。我们通过求解全热能方程来跟踪气体的热力学演化,同时也跟踪了尘埃温度的演化和气体的化学演化。我们模拟云与不同的金属丰度,并确定云的属性,在这一点上,它经历了重力破碎。当我们用一个简单的非气态物体(一个下沉粒子)替换非常致密、引力束缚和坍缩的区域时,我们将进一步坍缩到一个AU的尺度。我们的研究结果表明,对于金属丰度为10^{-5}Z_Solar,尘埃冷却产生低质量的碎片,因此有可能形成低质量的恒星。我们的结论是,尘埃冷却影响低金属丰度气体云的碎片,并在塑造恒星IMF中发挥重要作用,即使在这些非常低的金属丰度。我们发现,随着金属丰度的降低,特征碎片质量增加,但没有发现在我们目前的研究中检查的金属岩的范围内的IMF的行为的突然转变的证据。

英文摘要:

The theory for the formation of the first population of stars (Pop III) predicts a IMF composed predominantly of high-mass stars, in contrast to the present-day IMF, which tends to yield stars with masses less than 1 M_Solar. The leading theory for the transition in the characteristic stellar mass predicts that the cause is the extra cooling provided by increasing metallicity and in particular the cooling provided at high densities by dust. The aim of this work is to test whether dust cooling can lead to fragmentation and be responsible for this transition. To investigate this, we make use of high-resolution hydrodynamic simulations. We follow the thermodynamic evolution of the gas by solving the full thermal energy equation, and also track the evolution of the dust temperature and the chemical evolution of the gas. We model clouds with different metallicities, and determine the properties of the cloud at the point at which it undergoes gravitational fragmentation. We follow the further collapse to scales of an AU when we replace very dense, gravitationally bound, and collapsing regions by a simple and nongaseous object, a sink particle. Our results suggest that for metallicities as small as 10^{-5}Z_Solar, dust cooling produces low-mass fragments and hence can potentially enable the formation of low mass stars. We conclude that dust cooling affects the fragmentation of low-metallicity gas clouds and plays an important role in shaping the stellar IMF even at these very low metallicities. We find that the characteristic fragment mass increases with decreasing metallicity, but find no evidence for a sudden transition in the behaviour of the IMF within the range of metallicites examined in our present study.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑