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Variations in the Abundance Pattern of Extremely Metal-Poor Stars and Nucleosynthesis in Population III Supernovae

机译:III类超新星中极贫金属星的丰度模式变化和核合成

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We calculate nucleosynthesis in Population III supernovae (SNe) and compare the yields with various abundance patterns of extremely metal-poor (EMP) stars. We assume that the observed EMP stars are second-generation stars, which have the metal-abundance patterns of Population III SNe. Previous theoretical yields of Population III SNe cannot explain the trends in the abundance ratios among Fe-peak elements (Mn, Co, Ni, Zn)/Fe or the large C/Fe ratio observed in certain EMP stars with [Fe/H] -2.5. In this paper we show that if we introduce higher explosion energies and mixing fallback in the core-collapse SN models of M ~ 20-130 M☉, the above abundance features of both typical and C-rich EMP stars can be much better explained. We suggest that the abundance patterns of the [Fe/H] ~ -2.5 stars correspond to supernova yields with normal explosion energies, while those of the carbon unenhanced ([C/Fe] 1) stars with [Fe/H] -4 to -3 correspond to high-energy supernova yields. The abundance patterns of the C-rich ([C/Fe] 2) and low [Fe/H]( -5.5 ~ -3.5) stars can be explained with the yields of faint SNe that eject little 56Ni as observed in SN 1997D. In the supernova-induced star formation model, we can qualitatively explain why the EMP stars formed by the faint or energetic supernovae have lower [Fe/H] than the EMP stars formed by normal supernovae. We also examine how the abundance ratios among Fe-peak elements depend on the electron mole fraction Ye and conclude that a large explosion energy is still needed to realize the large Co/Fe and Zn/Fe ratios observed in typical EMP stars with [Fe/H] -3.5.
机译:我们计算人口III超新星(SNe)的核合成,并将产量与极贫金属(EMP)恒星的各种丰度模式进行比较。我们假设观测到的EMP恒星是第二代恒星,具有人口III SNe的金属丰度模式。先前关于III号SNe的理论产量无法解释铁峰元素(Mn,Co,Ni,Zn)/ Fe之间的丰度比或在某些具有[Fe / H]-的EMP星中观测到的大C / Fe比的趋势。 2.5。在本文中,我们表明,如果在M〜20-130 M-的核心坍塌SN模型中引入更高的爆炸能量并混合回落,则可以更好地解释典型的和富含C的EMP星的上述丰度特征。我们建议[Fe / H]〜-2.5星的丰度模式与具有正常爆炸能量的超新星产量相对应,而碳含量为[Fe / H] -4的未增强([C / Fe] <1)恒星的丰度模式对应到-3对应于高能超新星产量。富含C的([C / Fe] 2)和低[Fe / H](-5.5〜-3.5)恒星的丰度模式可以用SN 1997D中观测到的微弱的SNe射出很少的56Ni来解释。在超新星诱发的恒星形成模型中,我们可以定性地解释为什么微弱或高能超新星形成的EMP恒星比正常超新星形成的EMP恒星具有更低的[Fe / H]。我们还研究了铁峰元素之间的丰度比如何取决于电子摩尔分数Ye,并得出结论,要实现在具有[Fe / Fe的典型EMP恒星中观察到的大Co / Fe和Zn / Fe比,仍需要大的爆炸能量。 H] -3.5。

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