利用LAMOST搜寻富锂K巨星

The Search for the Lithium Rich K Giants with LAMOST

锂在~2MK时就被损耗,因而在恒星大气中表现出较低丰度.根据标准恒星演化理论,当演化至巨星分支并经历第1次挖掘过程后,锂元素丰度从原始的A(Li)≈3.3dex降低至A(Li)≤1.5dex.然而,约有1%的K巨星被发现A(Li)>1.5dex,被称为富锂巨星,甚至发现了一些超富锂A(Li)>3.3dex巨星,这些发现对标准恒星演化理论提出了挑战.根据富锂K巨星的特性,在郭守敬望远镜(LAMOST)海量的低分辨率光谱中开展了富锂K巨星搜寻工作;介绍了导致富锂过程的可能机制,探讨了这些理论的不足.

Lithium is easily destroyed at the temperature about 2 MK, thus it shows low abundances in stellar atmospheres. According to the standard stellar evolution models, the lithium abundance decreases from primordial A（Li） ≈3.3 dex to the value less than 1.5 dex in low mass stars. However, about 1 % of K giant stars have been shown to have lithium abundance higher than 1.5 dex,and they are termed as Li-rich giants,even some super-rich lithium （〉3.3 dex） giants have been found. These discoveries challenge the standard stellar evolution theory. In the light of the characteristics of lithium rich giants, we searched for this kind of stars with the low resolution spectra from LAMOST. The possible mechanism of lithium enrichment was introduced, and the shortages of these models were discussed.