C, N, O abundances in the most metal-poor damped Lyman alpha systems★
C, N, O abundances in the most metal-poor damped Lyman alpha systems★
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最贫金属阻尼莱曼 α 系统中的 C、N、O 丰度★
DOI：
10.1111/j.1365-2966.2008.12951.x
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发表时间：
2007
影响因子：
4.8
通讯作者：
F. Chaffee
中科院分区：
文献类型：
--
作者：
M. Pettini;B. Zych;C. Steidel;F. Chaffee
这项研究的重点是一些最贫金属阻尼Ly α（DLA）吸收已知的高红移类星体的光谱，使用新的和存档的观测获得的紫外线敏感的阶梯光栅光谱仪上的凯克和VLT望远镜。在这些系统中的吸收线的弱点和简单的速度结构，使我们能够测量几种元素的丰度，特别是那些C，N和O，一组是很难研究的DLAs更典型的金属丰度。我们发现，当氧丰度小于太阳的0.01/100时，高红移DLAs和亚DLAs中的C/O比与类似金属丰度的晕星相匹配，并且显示出比基于传统恒星产额的星系化学演化模型所预期的更高的值。此外，有迹象表明，在这些低金属丰度的N/O比也可能高于简单的预期，并可能表现出最低值，如百夫长和她的合作者在2003年提出的。这两个结果都可以解释为证据增强生产的C和N的大质量恒星在最初几集的星星形成，在我们的银河系和遥远的原星系被视为类星体吸收。在最近的一些模型计算中，恒星自转促进了恒星内部的混合，这可能意味着更高的恒星产额。我们简要地讨论了这些结果的相关性，目前的想法在星系际介质中的金属的起源和恒星初始质量函数的普遍性。
This study focuses on some of the most metal-poor damped Lyα (DLA) absorbers known in the spectra of high-redshift QSOs, using new and archival observations obtained with ultraviolet-sensitive echelle spectrographs on the Keck and VLT telescopes. The weakness and simple velocity structure of the absorption lines in these systems allow us to measure the abundances of several elements, and in particular those of C, N and O, a group that is difficult to study in DLAs of more typical metallicities. We find that when the oxygen abundance is less than ∼1/100 of solar, the C/O ratio in high-redshift DLAs and sub-DLAs matches that of halo stars of similar metallicity and shows higher values than expected from galactic chemical evolution models based on conventional stellar yields. Furthermore, there are indications that at these low metallicities the N/O ratio may also be above simple expectations and may exhibit a minimum value, as proposed by Centurion and her collaborators in 2003. Both results can be interpreted as evidence for enhanced production of C and N by massive stars in the first few episodes of star formation, in our Galaxy and in the distant protogalaxies seen as QSO absorbers. The higher stellar yields implied may have an origin in stellar rotation which promotes mixing in the stars' interiors, as considered in some recent model calculations. We briefly discuss the relevance of these results to current ideas on the origin of metals in the intergalactic medium and the universality of the stellar initial mass function.
DOI：
10.1051/0004-6361:20054328
发表时间：
2006-02
期刊：
arXiv: Astrophysics
影响因子：
--
作者：
P. Erni;P. Richter;C. Ledoux;P. Petitjean
通讯作者：
P. Erni;P. Richter;C. Ledoux;P. Petitjean