The Oxygen Abundance of HE 1327–2326
The Oxygen Abundance of HE 1327–2326
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DOI：
10.1086/500592
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发表时间：
2005-12
期刊：
影响因子：
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通讯作者：
A. Frebel;N. Christlieb;J. Norris;W. Aoki;M. Asplund
中科院分区：
文献类型：
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作者：
A. Frebel;N. Christlieb;J. Norris;W. Aoki;M. Asplund
从新获得的 VLT/UVES 光谱中，我们确定了 HE 1327-2326 的氧丰度，这是迄今为止已知最贫铁的恒星。紫外 OH 线产生一维 LTE 丰度 [O/Fe]OH = 3.7（亚巨星情况）和 [O/Fe]OH = 3.4（矮星情况）。使用 -1.0 dex 校正来解释对 OH 线形成的三维 (3D) 影响，丰度分别降低至我们采用的 [O/Fe] = 2.8 和 [O/Fe] = 2.5。如果没有 3D 校正，基于 UV OH 的丰度将与源自 O I 三重线的上限不一致：[O/Fe]trip < 2.8（亚巨星）和 [O/Fe]trip < 3.0（矮星）。我们还针对 3D 效果校正了先前确定的碳和氮丰度。 HE 1327-2326 的 O 丰度知识对其丰度模式的解释具有重要意义。大量的 O 丰度符合 HE 1327-2326 是一颗早期的 II 族恒星，由第一代超新星化学富集的物质形成。然而，我们得出的丰度并不排除其他可能性，例如人口 III 情景。
From a newly obtained VLT/UVES spectrum, we have determined the oxygen abundance of HE 1327-2326, the most iron-poor star known to date. Ultraviolet OH lines yield one-dimensional LTE abundances of [O/Fe]OH = 3.7 (subgiant case) and [O/Fe]OH = 3.4 (dwarf case). Using a correction of -1.0 dex to account for three-dimensional (3D) effects on OH line formation, the abundances are lowered to [O/Fe] = 2.8 and [O/Fe] = 2.5, respectively, which we adopt. Without 3D corrections, the UV OH-based abundance would be in disagreement with the upper limits derived from the O I triplet lines: [O/Fe]trip < 2.8 (subgiant) and [O/Fe]trip < 3.0 (dwarf). We also correct the previously determined carbon and nitrogen abundances for 3D effects. Knowledge of the O abundance of HE 1327-2326 has implications for the interpretation of its abundance pattern. A large O abundance is in accordance with HE 1327-2326 being an early Population II star that formed from material chemically enriched by a first-generation supernova. Our derived abundances, however, do not exclude other possibilities such as a Population III scenario.