Self-Enrichment in Globular Clusters: The Crucial Role Played by Oxygen

Results from photometry and high-resolution spectroscopy have demonstrated the existence of multiple populations in globular clusters, where one or more stellar generations stars coexist with original population. We study possibility that new generation(s) formed gas lost by intermediate mass (4–8 M⊙) during asymptotic giant branch (AGB) evolution, possibly after dilution residual pristine cluster. To this aim, we confront chemistry AGB ejecta distribution chemical composition NGC 6402. find a satisfactory consistency between observational evidence self-enrichment AGBs hypothesis is reached if mass-loss rates experienced for latter ∼10 times smaller than found solar metallicity counterparts same mass. also comment on importance knowledge oxygen abundance as key indicator extent nucleosynthesis at which belonging to second generation clusters formed, degree gas.