Nucleosynthetic signatures of the first stars
Nucleosynthetic signatures of the first stars
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DOI：
10.1038/nature03455
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发表时间：
2005-03
期刊：
影响因子：
64.8
通讯作者：
A. Frebel;W. Aoki;N. Christlieb;H. Ando;M. Asplund;P. Barklem;T. Beers;K. Eriksson;C. Fechner-C.-Fechne
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作者：
A. Frebel;W. Aoki;N. Christlieb;H. Ando;M. Asplund;P. Barklem;T. Beers;K. Eriksson;C. Fechner-C.-Fechne
化学上最原始的恒星对宇宙中形成的第一批恒星天体的性质提供了限制；这些天体中存在的氢、氦和微量锂以外的元素是在最早的恒星中通过核合成产生的。幸存的原始恒星中元素的相对丰度反映了第一批恒星的质量，因为核合成的路径对恒星质量非常敏感。已经提出了几个模型来解释巨星HE0107-5240丰度模式的起源，这是迄今已知的最严重的重元素缺乏。这里我们报道了一颗次巨星或主序星HE1327-2326的发现，它的铁丰度大约比HE0107-5240低2倍。这两颗恒星都显示出碳和氮相对于铁的极度过剩，这表明它们的丰度模式相似。然而，HE1327-2326出人意料的低锂高锶丰度挑战了现有的理论理解：没有一个模型预测到高锶丰度，也没有一个模型提供了与大多数贫金属星的数据相一致的锂贫化机制。
The chemically most primitive stars provide constraints on the nature of the first stellar objects that formed in the Universe; elements other than hydrogen, helium and traces of lithium present within these objects were generated by nucleosynthesis in the very first stars. The relative abundances of elements in the surviving primitive stars reflect the masses of the first stars, because the pathways of nucleosynthesis are quite sensitive to stellar masses. Several models,,,,have been suggested to explain the origin of the abundance pattern of the giant star HE0107–5240, which hitherto exhibited the highest deficiency of heavy elements known,. Here we report the discovery of HE1327–2326, a subgiant or main-sequence star with an iron abundance about a factor of two lower than that of HE0107–5240. Both stars show extreme overabundances of carbon and nitrogen with respect to iron, suggesting a similar origin of the abundance patterns. The unexpectedly low Li and high Sr abundances of HE1327–2326, however, challenge existing theoretical understanding: no model predicts the high Sr abundance or provides a Li depletion mechanism consistent with data available for the most metal-poor stars.