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[O/Fe] ESTIMATES FOR CARBON-ENHANCED METAL-POOR STARS FROM NEAR-INFRARED SPECTROSCOPY

机译:近红外光谱的碳增强金属贫乏恒星的[O / Fe]估计

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We report on oxygen abundances determined from medium-resolution near-infrared spectroscopy for a sample of 57 carbon-enhanced metal-poor (CEMP) stars selected from the Hamburg/ESO Survey. The majority of our program stars exhibit oxygen-to-iron ratios in the range +0.5 [O/Fe]+2.0. The [O/Fe] values for this sample are statistically compared to available high-resolution estimates for known CEMP stars as well as to high-resolution estimates for a set of carbon-normal metal-poor stars. Carbon, nitrogen, and oxygen abundance patterns for a sub-sample of these stars are compared to yield predictions for very metal-poor asymptotic giant branch (AGB) abundances in the recent literature. We find that the majority of our sample exhibit patterns that are consistent with previously studied CEMP stars having s-process-element enhancements and thus have very likely been polluted by carbon- and oxygen-enhanced material transferred from a metal-poor AGB companion.
机译:我们报告了从汉堡/ ESO调查中选择的57个碳增强的贫金属(CEMP)星样品的中分辨率近红外光谱确定的氧丰度。我们的大多数恒星表现出的氧铁比率在+0.5 <[O / Fe] <+ 2.0范围内。将该样品的[O / Fe]值与已知CEMP恒星的可用高分辨率估算值以及一组碳正态金属贫乏恒星的高分辨率估算值进行统计比较。将这些恒星的子样本的碳,氮和氧丰度模式与最近文献中极贫金属的渐近巨分支(AGB)丰度的产量预测进行了比较。我们发现,我们的大多数样本都表现出与先前研究过的具有s-过程元素增强的CEMP恒星相一致的模式,因此很可能已被贫金属AGB伴生的碳和氧增强物质污染。

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