报告人：符晓婷　 博士 （SISSA）

时间：2015年12月25日下午4：00

地点：东区理化大楼18层天文台报告厅

报告摘要：The abundance of Lithium constrains models of big bang nucleosynthesis, stellar structure and the age of stellar clusters. Lithium abundances therefore play a special role in our understanding of the universe. However, there are two major outstanding puzzles about stellar lithium abundances. Population II dwarfs are observed to possess lithium abundances in a plateau which is lower than the primordial value by a factor of three. Where does the lithium go to?  In red giant branch stars, lithium should be burnt because of their deep convective envelope, but about 1% of red giant stars exhibit glaring exceptions. Some of them even display lithium abundances higher than the primordial value. These stars cannot be explained by standard stellar evolution models. Where does the lithium come from? I will talk about these two puzzles and possible solutions from both  theoretical and observational perspectives.