论文标题
碳增强的莱曼极限系统：第一代恒星的签名？
A Carbon-enhanced Lyman Limit System: Signature of the First Generation of Stars?
论文作者
论文摘要
我们向$ z {\ rm abs} $ = 1.5441的lyman限制系统（LLS）介绍了对Quasar J134122.50+185213.9的研究。这是一个非常奇特的系统，具有强大的C I吸收，与中性氢柱密度相关的log $ n $（h i）（cm $^{ - 2} $）= 18.10，太小，无法将气体免受任何外部UV的范围。低电离吸收系表现出与单个成分一致的简单运动学结构。使用多云的模型来校正电离，我们发现气体的电离参数在$ - $ 4.5 $ <$ <$ <$ log $ $ $ $ $ <$ <$ <$ <$ - $ 4.2和气体密度$ -1.5 $ 1.5 $ <$ log $ n $（h）（cm $ $^{ - 3} $ <$ <$ $ <$ -1.2。这些型号表明，相对于铁，碳过多，[c/fe] $> $ 2.2 at [fe/h] $ \ sim $ $ - $ 1.6。这种金属丰度模式让人联想到银河系中检测到的碳增强金属贫困星。第一代超新星的金属富集为该系统中推断的丰度模式提供了合理的解释。
We present the study of a Lyman limit system (LLS) at $z_{\rm abs}$ = 1.5441 towards quasar J134122.50+185213.9 observed with VLT X-shooter. This is a very peculiar system with strong C I absorption seen associated with a neutral hydrogen column density of log $N$(H I) (cm$^{-2}$) = 18.10, too small to shield the gas from any external UV flux. The low ionization absorption lines exhibit a simple kinematic structure consistent with a single component. Using CLOUDY models to correct for ionization, we find that the ionization parameter of the gas is in the range $-$ 4.5 $<$ log $U$ $<$ $-$4.2 and the gas density $-$1.5 $<$ log $n$(H) (cm$^{-3}$) $<$ $-$1.2. The models suggest that carbon is overabundant relative to iron, [C/Fe] $>$ +2.2 at [Fe/H] $\sim$ $-$1.6. Such a metal abundance pattern is reminiscent of carbon-enhanced metal-poor stars detected in the Galaxy halo. Metal enrichment by the first generation of supernovae provides a plausible explanation for the inferred abundance pattern in this system.
