New evidence for the complex struscture of the RGB of Omega Cen

Abstract

We report on the complex structure of the red giant branch (RGB) of omega Cen, based on a new wide field and wide color baseline B and I photometry. Our color magnitude diagram (CMD) shows the presence of multiple populations along this branch, in particular we discovered an anomalous branch (RGB-a), which appears to be well separated from the bulk of the RGB stars. On the basis of our CMD and from the previous literature we conclude that (1) these stars, clearly identified as a separate population in our CMD, represent the extreme metal rich extension ([Ca/H]>-0.3) of the stellar content of omega Cen, and show anomalous abundances of s-process elements (as Ba and Zr) as well; (2) they are physical members of the omega Cen system; (3) they comprise ~ 5% of the stars of the whole system; (4) this component and the metal-intermediate one (-0.4>[Ca/H]>-1) have been found to share the same spatial distribution, both of them differing significantly from the most metal poor one ([Ca/H]<-1). This last evidence supports the hypothesis that metal rich components could belong to an independent (proto?) stellar system captured in the past by omega Cen.

arXiv comment5 pages, 3 figures, accepted for publication as ApJ Letter

References in corpus (6)

• Multiple Stellar Populations in the Globular Cluster omega Centauri as Tracers of a Merger Event
• The giant, horizontal and asymptotic branches of galactic globular clusters. I. The catalog, photometric observables and features
• The Abundance Spread Among Giants and Subgiants in the Globular Cluster Omega Centauri
• Blue Straggler Stars: The Spectacular Population in M80
• The Stellar Dynamics of Omega Centauri
• Spatial metallicity asymmetry in $\omega$ Centauri

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