EVOLUTION OF VERY MASSIVE POPULATION III STARS WITH MASS ACCRETION FROM PRE-MAIN SEQUENCE TO COLLAPSE
EVOLUTION OF VERY MASSIVE POPULATION III STARS WITH MASS ACCRETION FROM PRE-MAIN SEQUENCE TO COLLAPSE
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DOI：
10.1088/0004-637x/706/2/1184
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发表时间：
2009-02
期刊：
影响因子：
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通讯作者：
T. Ohkubo;K. Nomoto;H. Umeda;N. Yoshida;S. Tsuruta
中科院分区：
文献类型：
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作者：
T. Ohkubo;K. Nomoto;H. Umeda;N. Yoshida;S. Tsuruta
我们计算了零金属丰度第三族（Pop III）恒星的演化，这些恒星的质量通过吸积周围的气体而从初始质量101 M增加。我们的计算涵盖了整个演化阶段，从主序前，通过各种核燃烧阶段，通过最后的核心崩溃或对创建不稳定阶段。我们采用两套不同的恒星质量吸积率作为我们的基准模型。一个来自第一代（PopIII.1）恒星的宇宙学模拟，另一个来自受PopIII.1恒星辐射影响的第二代恒星的模拟。后者代表PopIII.2星的一个案例。我们还采用了包括辐射反馈效应的其他模型。我们发现Pop III.1恒星的最终质量可以达到1000 M的质量，超过了对不稳定超新星的质量范围（140-300 M）。这样的大质量恒星经历核心坍缩形成中等质量黑洞，这可能是合并树到超大质量黑洞的种子。另一方面，Pop III.2恒星的质量变小（约40-60 M），处于普通铁核坍缩恒星的质量范围内。这些恒星爆炸并喷射出重元素，有助于早期宇宙的化学富集，正如在银河系晕中极贫金属恒星的丰度模式中所观察到的那样。考虑到可能的吸积率范围很大，进一步的研究很重要，以确定这些基准模型是否真的是这种情况。
We calculate the evolution of zero-metallicity Population III (Pop III) stars whose mass grows from the initial mass of ∼1 M☉ by accreting the surrounding gases. Our calculations cover whole evolutionary stages from the pre-main sequence, via various nuclear burning stages, through the final core-collapse or pair-creation instability phases. We adopt two different sets of stellar mass accretion rates as our fiducial models. One is derived from a cosmological simulation of the first generation (PopIII.1) stars, and the other is derived from a simulation of the second generation stars that are affected by radiation from PopIII.1 stars. The latter represents one case of PopIII.2 stars. We also adopt additional models that include radiative feedback effects. We show that the final mass of Pop III.1 stars can be as large as ∼1000 M☉, beyond the mass range (140–300 M☉) for the pair-instability supernovae. Such massive stars undergo core-collapse to form intermediate-mass black holes, which may be the seeds for merger trees to supermassive black holes. On the other hand, Pop III.2 stars become less massive (≲40–60 M☉), being in the mass range of ordinary iron core-collapse stars. Such stars explode and eject heavy elements to contribute to chemical enrichment of the early universe as observed in the abundance patterns of extremely metal-poor stars in the Galactic halo. In view of the large range of possible accretion rates, further studies are important to see if these fiducial models are actually the cases.