ELECTRON-CAPTURE SUPERNOVAE AS THE ORIGIN OF ELEMENTS BEYOND IRON
ELECTRON-CAPTURE SUPERNOVAE AS THE ORIGIN OF ELEMENTS BEYOND IRON
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DOI：
10.1088/2041-8205/726/2/l15
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发表时间：
2010-09
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影响因子：
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通讯作者：
S. Wanajo;H. Janka;B. Mueller
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文献类型：
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作者：
S. Wanajo;H. Janka;B. Mueller
我们将电子俘获超新星（ECSNe）作为太阳系和银河系晕星中比铁重的元素的来源进行研究。在一个完全自洽的二维电子俘获超新星流体动力学爆炸模型的质量元热力学历史的基础上进行了核合成计算。我们发现，在一维模型中不存在的、电子丰度低至\(Y_{e,\text{min}} = 0.40\)的富中子对流团块，能够在核（准）平衡状态下有趣地产生铁族元素和\(N = 50\)的原子核之间的元素（从锌到锆，几乎没有镓）。我们的模型与贫r - 过程银河系晕星的锗、锶、钇和锆的丰度非常吻合，并将电子俘获超新星的发生限制在所有恒星核心坍缩事件的约\(4\%\)。如果还喷射出极少量\(Y_{e,\text{min}}\)略低至约\(0.30 - 0.35\)的额外物质——由于模型分辨率和二维性的限制，目前无法排除这种情况——一个弱r - 过程可以产生\(N = 50\)之后直至钯、银和镉的元素，正如在贫r - 过程恒星中所观测到的那样。
We examine electron-capture supernovae (ECSNe) as sources of elements heavier than iron in the solar system and in Galactic halo stars. Nucleosynthesis calculations are performed on the basis of thermodynamic histories of mass elements from a fully self-consistent, two-dimensional hydrodynamic explosion model of an ECSN. We find that neutron-rich convective lumps with an electron fraction down to Ye,min = 0.40, which are absent in the one-dimensional counterpart, allow for interesting production of elements between the iron group and N = 50 nuclei (from Zn to Zr, with little Ga) in nuclear (quasi-)equilibrium. Our models yield very good agreement with the Ge, Sr, Y, and Zr abundances of r-process-deficient Galactic halo stars and constrain the occurrence of ECSNe to ∼4% of all stellar core-collapse events. If tiny amounts of additional material with slightly lower Ye,min down to ∼0.30–0.35 were also ejected—which presently cannot be excluded because of the limitations of resolution and two dimensionality of the model—a weak r-process can yield elements beyond N = 50 up to Pd, Ag, and Cd as observed in the r-process-deficient stars.