Heavy-Element Nucleosynthesis in a Collapsar
Heavy-Element Nucleosynthesis in a Collapsar
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DOI：
10.1086/509908
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发表时间：
2006-02
期刊：
影响因子：
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通讯作者：
S. Fujimoto;M. Hashimoto;K. Kotake;S. Yamada
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文献类型：
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作者：
S. Fujimoto;M. Hashimoto;K. Kotake;S. Yamada
我们已经做了详细的计算的组成磁驱动的喷流喷射出的一颗恒星，基于长期的，磁流体动力学模拟的快速旋转，大质量（40兆）的星星在核心崩溃。我们遵循的演化约4000种核素的丰度从崩溃阶段的喷射阶段，并通过射流生成阶段使用两个大型核反应网络。我们发现，r-过程成功地在射流中操作，使U和Th合成丰富的祖时，有一个大的磁场（1012 G）和一个快速旋转的核心。喷流内部的丰度模式与太阳系中r元素的丰度模式相似。大约有0.01 M重的富中子核可以从这颗恒星中喷射出来。详细的丰度取决于质量模型的核性质、β衰变率和裂变，对于中子滴线附近的核。此外，我们还发现p核的产生是不需要籽晶的：不仅可以在喷流中大量合成轻p核，如74Se，78Kr，84Sr和92Mo，而且还可以合成重p核，113In，115Sn和138La。喷出物中p核的数量比核心坍缩超新星中的要多得多。特别是92Mo、113In、115Sn和138La，这些在这些超新星中缺乏的元素，都是在超新星的喷出物中大量产生的。
We have made detailed calculations of the composition of magnetically driven jets ejected from a collapsar, based on long-term, magnetohydrodynamic simulations of a rapidly rotating, massive (40 M☉) star during core collapse. We follow the evolution of the abundances of about 4000 nuclides from the collapse phase to the ejection phase and through the jet generation phase using two large nuclear reaction networks. We find that the r-process successfully operates in the jets, so that U and Th are synthesized abundantly when the progenitor has a large magnetic field (1012 G) and a rapidly rotating core. The abundance pattern inside the jets is similar to that of the r-elements in the solar system. About 0.01 M☉ of heavy, neutron-rich nuclei can be ejected from the collapsar. The detailed abundances depend on the nuclear properties of the mass model, β-decay rate, and fission, for nuclei near the neutron drip line. Furthermore, we find that p-nuclei are produced without seeds: not only can light p-nuclei, such as 74Se, 78Kr, 84Sr, and 92Mo, be abundantly synthesized in the jets, but also heavy p-nuclei, 113In, 115Sn, and 138La. The amounts of p-nuclei in the ejecta are much greater than those in core-collapse supernovae. In particular, 92Mo, 113In, 115Sn, and 138La, which are deficient in these supernovae, are produced significantly in the collapsar ejecta.