📝 SummarXiv

Abstract

\omega}Centauri ({\omega}Cen) is the most enigmatic Galactic globular cluster (GC), with unmatched chemical complexity. We combine photometric and spectroscopic catalogs to identify its distinct stellar populations and to investigate their spatial distribution and chemical properties, uncovering new insights into the cluster's formation history. We identify the iron-poor stars commonly found in GCs: the first population (1P), with halo-like chemical composition, and the second population (2P), enriched in elements produced by p-capture processes. Similarly, we divided the iron-rich stars (the anomalous stars) into two groups: the AI and the AII, exhibiting light-element abundance distributions similar to 1P and 2P stars, respectively. The wide extension of our dataset (five times the half-light radius) allowed us to directly and unambiguously compare the fraction of these populations at different radii. We find that 2P and AII stars are more centrally concentrated than the 1P and AI. The remarkable similarities between the 1P-2P and AI-AII radial distributions strongly suggest 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') self-enrichment, and that 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. 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.