The spreads in chemical abundances inferred by recent precision observations suggest that some or possibly all globular clusters can no longer be considered as simple stellar populations. The most striking case is omega Cen in the sense that its bluest main-sequence despite its high metallicity demands an extreme helium abundance of Y > 0.4. I focus on this issue of "the extreme helium population problem" in this review.
Cite
@article{arxiv.0903.2891,
title = {Multiple Population Theory: Extreme helium population problem},
author = {Sukyoung K. Yi},
journal= {arXiv preprint arXiv:0903.2891},
year = {2009}
}
Comments
10 pages, Review at the IAUS258 (The Ages of Stars) in Baltimore