omega Cen stars abundances

The remarkable similarities between the 1P-2P and AI-AII radial distributions strongly suggests that these two groups of stars originated from similar mechanisms. Our chemical analysis indicates that the 1P and AI stars (the lower stream) developed their inhomogeneities through core-collapse supernova (and possibly other massive stars' ejecta) self-enrichment, as supported by their increasing alpha-element abundances with [Fe/H].

These populations contributed p-capture-processed material to the intracluster medium, from which the chemically extreme 2P and AII stars (the upper stream) formed. Additional polluters-such as intermediate-mass asymptotic giant branch stars and Type Ia supernovae-likely played a role in shaping the AII population. Finally, we propose that 2P and AII stars with intermediate light-element abundances (the middle stream) formed via dilution between the pure ejecta that created the upper stream and lower-stream material.