2006/03/31 by Masataka Fukugita, Masahiro Kawasaki · 5 citations
Physics and Astronomy · #Astronomy and Astrophysical Research #Galaxies: Formation, Evolution, Phenomena #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/505109
published as Astrophys.J.646:691-695,2006 · 12 pages, 3 figures, misplaced figures are corrected, typos in Table1 are corrected
openalex publication_date 2006/07/28 · arxiv created 2006/11/09 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/01
A reanalysis is made for the helium abundance determination for the Izotov-Thuan spectroscopic sample of extragalactic H II regions. We find that the effect of underlying stellar absorption of the He I lines, which is more important for metal-poor systems, affects significantly the inferred primordial helium abundance Y p obtained in the zero-metallicity limit and the slope of linear extrapolation, dY / dZ . This brings Y p from 0.234 ± 0.004 to 0.250 ± 0.004 and dY / dZ = 4.7 ± 1.0 to 1.1 ± 1.4. Conservatively, this indicates the importance of the proper understanding of underlying stellar absorption for accurate determinations of the primordial helium abundance to the error of δ Y p ≃ 0.002-0.004.