A minimum dilution scenario for supernovae and consequences for extremely metal-poor stars
A minimum dilution scenario for supernovae and consequences for extremely metal-poor stars
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DOI：
10.1093/mnras/staa2624
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发表时间：
2020-06
影响因子：
4.8
通讯作者：
M. Magg;T. Nordlander;S. Glover;C. Hansen;M. Ishigaki;A. Heger;R. Klessen;C. Kobayashi;K. Nomoto
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文献类型：
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作者：
M. Magg;T. Nordlander;S. Glover;C. Hansen;M. Ishigaki;A. Heger;R. Klessen;C. Kobayashi;K. Nomoto
迄今为止，还没有通过直接观测发现任何不含金属的恒星。限制其性质的最常见方法是在最贫金属恒星的光谱中搜索第一代恒星及其超新星（SN）中产生的化学元素。在这种方法中，将模拟的SN产量与在金属极度贫乏的恒星中观察到的丰度模式进行比较。该方法通常仅使用丰度比，即产量被稀释到观察到的水平。遵循球对称性的通常假设，我们计算了一个 SN 可以混合的简单质量下限，并发现它与所有已发表的星际介质中早期化学富集的模拟一致。对于三种不同的情况，我们证明这种稀释限制可以改变丰度拟合的结论。微型晕中超新星爆炸模拟中发现的稀释度与许多丰度拟合中假设的稀释度之间存在很大差异。限制稀释可以显着改变超新星是观测到的 CEMP-no 恒星的可能祖先的可能性。特别是，一些微弱的、产量非常低的超新星，被建议作为 SMSS0313−6708 丰度模式的模型，无法解释测量到的金属丰度，因为它们预测的金属产量太小了两个数量级。总而言之，这里提出的新稀释模型强调需要更好地理解非球面超新星的混合和稀释行为。
To date no metal-free stars have been identified by direct observations. The most common method of constraining their properties is searching the spectra of the most metal-poor stars for the chemical elements created in the first stars and their supernova (SN). In this approach, modelled SN yields are compared to the observed abundance patterns in extremely metal-poor stars. The method typically only uses the abundance ratios, i.e. the yields are diluted to the observed level. Following the usual assumption of spherical symmetry we compute a simple lower limit of the mass an SN can mix with and find that it is consistent with all published simulations of early chemical enrichment in the interstellar medium. For three different cases, we demonstrate that this dilution limit can change the conclusions from the abundance fitting. There is a large discrepancy between the dilution found in simulations of SN explosions in minihaloes and the dilution assumed in many abundance fits. Limiting the dilution can significantly alter the likelihood of which supernovae are possible progenitors of observed CEMP-no stars. In particular, some of the faint, very low yield SNe, which have been suggested as models for the abundance pattern of SMSS0313−6708, cannot explain the measured metal abundances, as their predicted metal yields are too small by two orders of magnitude. Altogether, the new dilution model presented here emphasizes the need to better understand the mixing and dilution behaviour of aspherical SNe.