The Magellanic Clouds and the Primordial Helium Abundance
Loading...
Date
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
Description
A new determination of the pregalactic helium abundance based on the Magellanic Clouds H II regions is discussed. This determination amounts to Yp = 0.2345 +- 0.0030 and is compared with those derived from giant extragalactic H II regions in systems with extremely low heavy elements content. It is suggested that the higher primordial value derived by other authors from giant H II region complexes could be due to two systematic effects: the presence of neutral hydrogen inside the helium Stromgren sphere and the presence of temperature variations inside the observed volume.
10 pages, 1 figure, IAU Symposium 198
10 pages, 1 figure, IAU Symposium 198