1. Photoionization Models of Metal-poor Extragalactic H o Regions And the Primordial Helium Abundance
- Author
-
A. Peimbert, M. Peimbert, and V. Luridiana
- Subjects
II Regions ,Abundances [ISM] ,Física, Astronomía y Matemáticas ,ISM - II Regions - ISM ,ISM [Galaxies] ,Astrophysics::Solar and Stellar Astrophysics ,Abundances [Galaxies] ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Abundances ,Galaxies ,Astrophysics::Galaxy Astrophysics ,Abundances - Galaxies - Abstract
"We discuss the effects of collisional enhancement of Balmer lines on the determination of the primordial helium abundance. To this aim, we present a photoionization model of the metal-poor extragalactic H II region SBS 0335-052. We show that the derived helium abundance (Y ) of this H II region depends on the amount of collisional excitation affecting the Balmer lines, both directly (through an underestimation of the actual He/H ratio) and indirectly (through an overestimation of the interstellar reddening). We detail how each of these effects affects the derived value of Y ."
- Published
- 2003