Systematic Effects and a New Determination of the Primordial Abundance of4He anddY/dZfrom Observations of Blue Compact Galaxies

Authors :: Yuri I. Izotov
Trinh X. Thuan
Source :: The Astrophysical Journal. 602:200-230
Publication Year :: 2004
Publisher :: American Astronomical Society, 2004.
Abstract: We use spectroscopic observations of a sample of 82 HII regions in 76 blue compact galaxies to determine the primordial helium abundance Yp and the slope dY/dZ from the Y-O/H linear regression. To improve the accuracy of the dY/dZ measurement, we have included new spectrophotometric observations of 33 HII regions which span a large metallicity range, with oxygen abundance 12+log(O/H) varying between 7.43 and 8.30 (Zsun/30<br />Comment: 53 pages, 3 Postscript figures, accepted for publication in the Astrophysical Journal

Subjects :: Physics
Metallicity
Astrophysics (astro-ph)
FOS: Physical sciences
Astronomy and Astrophysics
Astrophysics
Omega
Galaxy
Big Bang nucleosynthesis
Deuterium
Space and Planetary Science
Excited state
Emission spectrum
Collisional excitation

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