The role of asymptotic giant branch stars in galactic chemical evolution

Abstract

The chemical evolution of the Universe is governed by the nucleosynthesis output from stars, which is determined primarily by the initial stellar mass. Stars less massive than about 8-10M⊙, depending on metallicity, experience recurrent mixing events on the giant branches that can significantly change the surface composition of the envelope, with observed enrichments in lithium, carbon, nitrogen, fluorine, and heavy elements synthesized by the slow neutron capture process (the s-process). It is during the asymptotic giant branch (AGB) phase of stellar evolution when the richest nucleosynthesis occurs. This phase is also characterized by intense mass loss, which releases the nucleosynthesis products into the interstellar medium. The stellar yields available for single stars with masses up to about 10M⊙ are reviewed, along with a broader discussion of the role that AGB stars play in the chemical evolution in galaxies and stellar systems. Show more