Measurements of 4He in metal-poor extragalactic H ii regions: the primordial Helium abundance and the ΔY/ΔO ratio
Abstract
We present a review on the determination of the primordial helium abundance Yp, based on the study of hydrogen and helium recombination lines in extragalactic H ii regions. We also discuss the observational determinations of the increase of helium to the increase of oxygen by mass ΔY/ΔO, and compare them with predictions based on models of galactic chemical evolution.
- Publication:
-
Light Elements in the Universe
- Pub Date:
- April 2010
- DOI:
- arXiv:
- arXiv:0912.0764
- Bibcode:
- 2010IAUS..268...91P
- Keywords:
-
- ISM: abundances – H ii regions – galaxies: abundances;
- evolution;
- irregular – Galaxy: disk – early universe;
- Astrophysics - Cosmology and Nongalactic Astrophysics;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- 10 pages, 2 figures. To appear in Light elements in the Universe, Proceedings IAU Symposium No 268