Lithium in red giants: the roles of the He-core flash and the luminosity bump

ABSTRACT Lithium abundances for red giants in the GALAH DR3 survey are studied. The rare examples of Li-enriched stars with A(Li) ≥1.5 confirmed to be He-core burning belonging or evolved from clump similar masses and metallicity: M ≃ 1.1 ± 0.2 M⊙ [Fe/H] −0.3 0.3. Li enrichment over abundance present a star’s predecessor at tip giant branch likely occurs all these stars. Examination elemental (C Eu) catalogue shows no anomalous and, particular, dependence on abundance, which ranges least five dex. synthesis is attributed flash occurring branch. Models Modules Experiments Stellar Astrophysics (MESA) match observed evolution along but only low effective temperature end spread giants. Run fairly well reproduced by MESA models. A speculation presented that series flashes not leads 7Li internal reservoir 3He also may lead restructuring leading about constant luminosity. Giants exhibiting marked enrichments found other evolutionary phases directly associated luminosity bump increase does exceed 0.3