Bibcode
Peimbert, Manuel; Peimbert, Antonio; Luridiana, Valentina; Ruiz, María Teresa
Referencia bibliográfica
Star Formation Through Time, ASP Conference Proceedings, Vol. 297, held 24-28 September 2002 in Granada, Spain. Edited by Enrique Perez, Rosa M. Gonzalez Delgado and Guillermo Tenorio-Tagle. ISBN: 1-58381-144-3, 2003, p.81
Fecha de publicación:
0
2003
Número de citas
20
Número de citas referidas
14
Descripción
Recent advances on the quest to determine the primordial or pregalactic
helium abundance, Yp, are reviewed. There are seven problems affecting
the He/H abundance determinations of H II regions that are briefly
discussed: the underlying absorption lines in the observed spectra, the
ionization, temperature, and density structures of each object, the
collisional contribution to the intensity of the He I and H I lines, the
optical thickness of the He I lines, and the extrapolation to derive Yp
based on the Y and O/H values.