On 7Li Enrichment by Low Mass Metal Poor Red Giant Branch Stars

Abstract

First-ascent red giants with strong and very strong Li lines have just been discovered in globular clusters. Using the stellar internal prompt 7Li enrichment - mass loss scenario, we explore the possibility of 7Li enrichment in the interstellar matter of the globular cluster M3 produced by these Li-rich giants. We found that enrichment as large as 70% or more compared to the initial 7Li content of M3 can be obtained during the entire life of this cluster. However, due to the several crossings of M3 into the Galactic plane, the new 7Li will be very probably removed by ram pressure into the disk. Globular clusters appear then as possible new sources of 7Li in the galactic disk. It is also suggested that the known Na/Al variations in stars of globular clusters could be somehow related to the 7Li variations and that the cool bottom mixing mechanism acting in the case of 7Li could also play a role in the case of Na and Al surface enrichments.