Pop III i-process nucleosynthesis and the elemental abundances of SMSS J0313-6708 and the most iron-poor stars
Pop III i-process nucleosynthesis and the elemental abundances of SMSS J0313-6708 and the most iron-poor stars
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DOI：
10.1093/mnrasl/slx190
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发表时间：
2017-10
影响因子：
4.8
通讯作者：
O. Clarkson;O. Clarkson;F. Herwig;F. Herwig;M. Pignatari;M. Pignatari
中科院分区：
文献类型：
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作者：
O. Clarkson;O. Clarkson;F. Herwig;F. Herwig;M. Pignatari;M. Pignatari
© 2017作者（S）。由牛津大学出版社代表皇家天文学会出版。在45 M的大质量恒星模型中，我们研究了壳层He燃烧过程中的高能吸氢事件，导致了log（LH/L λ）~ 13的H燃烧光度。为了跟踪可能发生在这样的事件的核合成，我们运行了一系列的单区核合成模型中发现的恒星演化模型的典型条件。这样的核合成条件可能导致i过程中子密度高达~ 1013 cm-3。由此产生的模拟丰度模式，其中Mg来自He燃烧和Ca来自i过程，与目前已知的最缺铁的星星SMSS J031300.36-670839.3的一般观测模式一致。然而，Na在这些i-过程条件下也有效地产生，并且预测超过观测值约2.5 dex。虽然这可能排除了SMSS J031300.36-670839.3的这种模型，但典型的氦燃烧i过程和高于太阳的[Na/Mg]、[Mg/Al]和低[Ca/Mg] i过程的特征很好地再现了两颗铁含量最低的恒星HE 1017-5240和HE 1327-2326的丰度特征。i过程没有达到Fe，而Fe必须来自低水平的额外富集。超贫金属或Pop III大质量恒星的CEMP过程可能能够解释在一些最贫金属的CEMP-无恒星中观察到的某些丰度模式。
© 2017 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society. We have investigated a highly energetic H-ingestion event during shell He burning leading to H-burning luminosities of log (L H /L ⊙ ) ~ 13 in a 45M⊙ Pop III massive stellar model. In order to track the nucleosynthesis which may occur in such an event, we run a series of single-zone nucleosynthesis models for typical conditions found in the stellar evolution model. Such nucleosynthesis conditions may lead to i-process neutron densities of up to ~10 13 cm -3 . The resulting simulation abundance pattern, where Mg comes from He burning and Ca from the i process, agrees with the general observed pattern of the most iron-poor star currently known, SMSS J031300.36-670839.3. However, Na is also efficiently produced in these i-process conditions, and the prediction exceeds observations by ~2.5 dex. While this probably rules out this model for SMSS J031300.36-670839.3, the typical i-process signature of combined He burning and i process of higher than solar [Na/Mg] , [Mg/Al], and low [Ca/Mg] is reproducing abundance features of the two next most iron-poor stars HE 1017-5240 and HE 1327-2326 very well. The i process does not reach Fe which would have to come from a low level of additional enrichment. i process in hyper-metal-poor or Pop III massive stars may be able to explain certain abundance patterns observed in some of the most metal-poor CEMP-no stars.