Journal Article

On the origin of the helium-rich population in ω Centauri

D. Romano, M. Tosi, M. Cignoni, F. Matteucci, E. Pancino and M. Bellazzini

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 401, issue 4, pages 2490-2498
Published in print February 2010 | ISSN: 0035-8711
Published online January 2010 | e-ISSN: 1365-2966 | DOI:
On the origin of the helium-rich population in ω Centauri

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To study the possible origin of the huge helium enrichment attributed to the stars on the blue main sequence of ω Centauri, we make use of a chemical evolution model that has proven able to reproduce other major observed properties of the cluster, namely its stellar metallicity distribution function, age–metallicity relation and trends of several abundance ratios with metallicity. In this framework, the key condition to satisfy all the available observational constraints is that a galactic-scale outflow develops in a much more massive parent system, as a consequence of multiple supernova explosions in a shallow potential well. This galactic wind must carry out preferentially the metals produced by explosive nucleosynthesis in supernovae, whereas elements restored to the interstellar medium through low-energy stellar winds by both asymptotic giant branch (AGB) stars and massive stars must be mostly retained. Assuming that helium is ejected through slow winds by both AGB stars and fast-rotating massive stars, the interstellar medium of ω Centauri's parent galaxy gets naturally enriched in helium in the course of its evolution.

Keywords: stars: AGB and post-AGB; stars: mass-loss; globular clusters: general; globular clusters: individual: ω Cen; galaxies: evolution; galaxies: star clusters

Journal Article.  7574 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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