Volume 448, Number 2, March III 2006
|Page(s)||L37 - L41|
|Published online||24 February 2006|
Letter to the Editor
On the origin of the high helium sequence in Centauri
Geneva Observatory, 1290 Sauverny, Switzerland e-mail: [andre.maeder;georges.meynet]@obs.unige.ch
Accepted: 21 January 2006
The blue Main Sequence (bMS) of ω Cen implies a ratio of helium to metal enrichment , which is a major enigma. We show that rotating models of low metallicity stars, which account for the anomalous abundance ratios of extremely metal poor stars, are also useful for understanding the very high ratio in ω Cen. Models of massive stars with moderate initial rotation velocities produce stellar winds with large He- and N-excesses, but without the large C- (and O-) excesses made by very fast rotation, in agreement with the observed chemical abundance ratios in ω Cen. It is still uncertain whether the abundance peculiarities of ω Cen result from the fact that the high velocity contributions of supernovae escaped the globular cluster, usually considered as a tidally stripped core of a dwarf galaxy. Another possibility is a general dominance of wind ejecta at very low Z, due to the formation of black holes. Some abundance and isotopic ratios like , , , , and may allow us to further discriminate between these scenarios and between the AGB and massive star contributions.
Key words: stars: ω Centauri / helium / stars: evolution
© ESO, 2006
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.