arXiv 0704.04772007-04-04astro-ph

早期宇宙中从第一颗星到第二颗星的转变

The Transition from the First Stars to the Second Stars in the Early Universe

Britton D. Smith, Steinn Sigurdsson

备注：: 13 pages, 3 color figures, 1 table, submitted to ApJL
DOI：: 10.1086/518692

摘要：

在数值模拟中，我们观察到在金属丰度为10^-3 Z太阳时，从奇异的高质量恒星形成模式到低质量主导模式的急剧转变。我们采用了一种新的方法，包括从金属辐射冷却到自适应网格细化流体动力学模拟。我们的研究结果说明了第一批恒星产生的金属如何导致从Pop III恒星的高质量恒星形成模式过渡到今天占主导地位的低质量模式。我们在标准的Lambda CDM模型中进行了宇宙学初始条件下的流体动力学模拟，金属丰度从0到10^-2 Z太阳能，红移为99。模拟一直进行到在5 x 10^5兆太阳暗物质晕的中心形成一个致密的核心，z约为18。对中心1兆太阳核的分析表明，两个金属丰度最低的模拟结果Z = 0和10^-4 Z太阳核包含一个质量占99%的团块，而两个金属丰度分别为Z = 10^-3和10^-2 Z太阳核的模拟结果各包含两个质量占大部分的团块。Z = 10^-3的Zsolar模拟还产生了两个质量在10^-2到10^-1 Msolar之间的低质量原恒星天体。Z >= 10^-3 Zsolar的气体能够冷却到CMB的温度，这为最小碎裂质量设定了一个下限。这表明第二代恒星产生了一个质量较低的恒星光谱，但平均而言仍然比本地宇宙中形成的恒星质量更大。

英文摘要：

We observe a sharp transition from a singular, high-mass mode of star formation, to a low-mass dominated mode, in numerical simulations, at a metallicity of 10^-3 Zsolar. We incorporate a new method for including the radiative cooling from metals into adaptive mesh-refinement hydrodynamic simulations. Our results illustrate how metals, produced by the first stars, led to a transition from the high-mass star formation mode of Pop III stars, to the low-mass mode that dominates today. We ran hydrodynamic simulations with cosmological initial conditions in the standard LambdaCDM model, with metallicities, from zero to 10^-2 Zsolar, beginnning at redshift, z = 99. The simulations were run until a dense core forms at the center of a 5 x 10^5 Msolar dark matter halo, at z ~ 18. Analysis of the central 1 Msolar core reveals that the two simulations with the lowest metallicities, Z = 0 and 10^-4 Zsolar, contain one clump with 99% of the mass, while the two with metallicities, Z = 10^-3 and 10^-2 Zsolar, each contain two clumps that share most of the mass. The Z = 10^-3 Zsolar simulation also produced two low-mass proto-stellar objects with masses between 10^-2 and 10^-1 Msolar. Gas with Z >= 10^-3 Zsolar is able to cool to the temperature of the CMB, which sets a lower limit to the minimum fragmentation mass. This suggests that the second generation stars produced a spectrum of lower mass stars, but were still more massive on average than stars formed in the local universe.

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。

摘要：

英文摘要：

相关论文