Evidence for Lithium Destruction and Synthesis in Main-Sequence and Subgiant Stars of about Solar Mass

Abstract

Herbig’s extensive work on lithium abundances in solar-type stars on and near the main sequence, suggested to him that for these stars the lithium abundance might be some simple, decreasing function of age. If this were the full story we should expect a low lithium abundance in subgiants of about solar mass. However, already in Herbig’s work there were one or two stars with lithium abundance about 10 times the Greenstein-Richardson solar value whose trigonometrical parallaxes showed them to be possible subgiants. Other subgiants with high lithium abundances have been found by Wallerstein and at Pretoria. These results suggest that solar-mass stars are able to synthesise fresh lithium in or just prior to their subgiant phase.