Stellar Yields of Rotating First Stars. II. Pair-instability Supernovae and Comparison with Observations
Stellar Yields of Rotating First Stars. II. Pair-instability Supernovae and Comparison with Observations
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DOI：
10.3847/1538-4357/aab95f
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发表时间：
2018-03
期刊：
影响因子：
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通讯作者：
Koh Takahashi;T. Yoshida;H. Umeda
中科院分区：
文献类型：
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作者：
Koh Takahashi;T. Yoshida;H. Umeda
最近的理论预测，第一颗恒星诞生时的初始质量为 ≳100 M⊙。对不稳定超新星（PISN）是此类大质量恒星的共同命运。我们的最终目标是通过进行丰度分析来证明 PISNe 的存在，从而证明早期宇宙中初始质量函数的高质量性质，其中假设的第一颗恒星的属性受到贫金属恒星丰度的限制。为了确定可靠和有用的丰度，我们首次研究了旋转和非旋转祖细胞的 PISN 核合成。我们表明，PISNe 的初始质量和 CO 核心质量范围取决于包络结构：开发膨胀包络的非磁性旋转模型的 CO 质量变化范围较低，为 ∼70–125 M⊙，而具有收缩包络的非旋转和磁性旋转模型的范围为 ∼80–135 M⊙。然而，我们发现旋转和非旋转祖细胞的爆炸产量没有显着差异，除了非磁性旋转模型中产生大量氮气之外。此外，我们对理论产量和大量贫金属恒星丰度样本进行了首次系统比较。我们发现，预测的低[Na/Mg]~-1.5和高[Ca/Mg]~0.5-1.3丰度比对于区分PISN特征和正常贫金属恒星丰度是最重要的，并确认目前观察到的贫金属恒星没有与PISN丰度匹配。对未检测进行了广泛的讨论。
Recent theory predicts that first stars are born with a massive initial mass of ≳100 M⊙. Pair-instability supernova (PISN) is a common fate for such massive stars. Our final goal is to prove the existence of PISNe and thus the high-mass nature of the initial mass function in the early universe by conducting abundance profiling, in which properties of a hypothetical first star is constrained by metal-poor star abundances. In order to determine reliable and useful abundances, we investigate the PISN nucleosynthesis taking both rotating and nonrotating progenitors for the first time. We show that the initial and CO core mass ranges for PISNe depend on the envelope structures: nonmagnetic rotating models developing inflated envelopes have a lower shifted CO mass range of ∼70–125 M⊙, while nonrotating and magnetic rotating models with deflated envelopes have a range of ∼80–135 M⊙. However, we find no significant difference in explosive yields from rotating and nonrotating progenitors, except for large nitrogen production in nonmagnetic rotating models. Furthermore, we conduct the first systematic comparison between theoretical yields and a large sample of metal-poor star abundances. We find that the predicted low [Na/Mg] ∼ −1.5 and high [Ca/Mg] ∼0.5–1.3 abundance ratios are the most important to discriminate PISN signatures from normal metal-poor star abundances, and confirm that no currently observed metal-poor star matches with the PISN abundance. An extensive discussion on the nondetection is presented.