Iron-peak Element Abundances in Warm Very Metal-poor Stars
Iron-peak Element Abundances in Warm Very Metal-poor Stars
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DOI：
10.3847/1538-4357/accd62
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发表时间：
2023-04
期刊：
影响因子：
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通讯作者：
C. Sneden;A. Boesgaard;J. Cowan;I. Roederer;E. A. Den Hartog;J. Lawler
中科院分区：
文献类型：
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作者：
C. Sneden;A. Boesgaard;J. Cowan;I. Roederer;E. A. Den Hartog;J. Lawler
我们已经导出了 37 颗主序关闭非常贫金属恒星 ([Fe/H] ≲−2.1) 的 Mg、Ca 和 Fe 族元素 Sc 到 Zn (Z = 21−30) 的新详细丰度。我们分析了最初为铍丰度调查收集的 Keck HIRES 光学和近紫外高信噪比光谱。通常使用约 400 个 Fe 族线以及每颗恒星准确的实验室跃迁概率，我们确定了 10 种 Fe 族元素以及 α 元素 Mg 和 Ca 的中性和电离物质的准确 LTE 金属丰度和丰度比。我们发现六种元素具有良好的中性/离子丰度一致性，这些元素在我们的恒星中在 3100–5800 Å 范围内具有可检测到的两种物种的跃迁。早期关于相关 Sc−Ti−V 相对丰度的报道已得到证实，并且似乎随着金属丰度的降低而缓慢增加。向该元素三重奏中添加 Zn；在最低金属丰度范围内，它似乎也越来越过剩。 Co似乎模仿了Zn的行为，但围绕其丰度可靠性的问题影响了它的解释。
We have derived new detailed abundances of Mg, Ca, and the Fe-group elements Sc through Zn (Z = 21−30) for 37 main-sequence turnoff very metal-poor stars ([Fe/H] ≲−2.1). We analyzed Keck HIRES optical and near-UV high signal-to-noise spectra originally gathered for a Be abundance survey. Using typically ∼400 Fe-group lines with accurate laboratory transition probabilities for each star, we have determined accurate LTE metallicities and abundance ratios for neutral and ionized species of the 10 Fe-group elements as well as α elements Mg and Ca. We find good neutral/ion abundance agreement for the six elements that have detectable transitions of both species in our stars in the 3100–5800 Å range. Earlier reports of correlated Sc−Ti−V relative overabundances are confirmed, and appear to slowly increase with decreasing metallicity. To this element trio we add Zn; it also appears to be increasingly overabundant in the lowest-metallicity regimes. Co appears to mimic the behavior of Zn, but issues surrounding its abundance reliability cloud its interpretation.