A Search for Lithium-rich Giant Stars
A Search for Lithium-rich Giant Stars
复制标题
DOI：
10.1086/191375
复制
发表时间：
1984-03
影响因子：
8.7
通讯作者：
Jeffery A. Brown;C. Sneden;D. Lambert;Edward Dutchover
中科院分区：
文献类型：
--
作者：
Jeffery A. Brown;C. Sneden;D. Lambert;Edward Dutchover
从DDO光度表中选出644颗亮G-K巨星，测定了它们的锂丰度或上限。其中两颗巨星的表面锂丰度接近星际介质和年轻主序星的宇宙值，另外八颗巨星的锂含量远远超过标准预测。这些富锂巨星中至少有一部分被证明已经演化到具有对流混合包层的阶段，无论是来自低表面碳同位素比的直接证据，还是来自它们的H-R图位置的间接证据。建议的独特条件，可能已经允许这些恒星产生或吸积新的锂为他们的表面层，或只是为了保护从破坏其初始的锂含量。剩余恒星的锂丰度表明，巨星很少符合标准的第一次挖掘理论的期望;平均额外的锂破坏需要约1.5 dex。这些巨人的演化状态和他们的平均质量进行了简要的讨论，并与银河系化学演化的预测的巨人的Li分布进行了比较。参考文献110篇。
Lithium abundances or upper limits have been determined for 644 bright G-K giant stars selected from the DDO photometric catalog. Two of these giants possess surface lithium abundances approaching the cosmic value of the interstellar medium and young main-sequence stars, and eight more giants have Li contents far in excess of standard predictions. At least some of these Li-rich giants are shown to be evolved to the stage of having convectively mixed envelopes, either from the direct evidence of low surface carbon isotope ratios, or from the indirect evidence of their H-R diagram positions. Suggestions are given for the unique conditions that might have allowed these stars to produce or accrete new lithium for their surface layers, or simply to preserve from destruction their initial lithium contents. The lithium abundance of the remaining stars demonstrates that giants only very rarely meet the expectations of standard first dredge-up theories; the average extra Li destruction required is about 1.5 dex. The evolutionary states of these giants and their average masses are discussed briefly, and the Li distribution of the giants is compared to predictions of Galactic chemical evolution. 110 refs.