About two lithium problems

Abstract

Among the metal-poor dwarfs (Population II), a few are enriched in Nitrogen. Surprisingly, in spite of this peculiarity, their lithium abundance is similar to the Li abundance of the other dwarfs. Several scenarios of nitrogen enrichment are discussed, none is completely satisfactory, the most likely is a contamination by some very highly N-rich matter. But it could be speculated that these N-rich dwarfs may perhaps be stars escaped from N-rich globular clusters. An homogeneous analysis of this class of stars could be useful.

The rather low level of the lithium abundance in the old dwarfs, contrasting with the high level found in the Population I, requires a surprisingly large and rapid production of Li. Recent observations show in one Population I red giant, a very high lithium abundance. This observation, in agreement with some predictions of some theoretical models of giants and/or AGB stars is very encouraging.