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Blue Compact Galaxies and the Primordial Helium Abundance Determination

Published online by Cambridge University Press:  14 August 2015

Y.I. Izotov  and
T.X. Thuan
Y.I. Izotov
Affiliation:
Main Astronomical Observatory, Ukrainian National Academy of Sciences Goloseevo, Kiev-22, 252650, Ukraine
T.X. Thuan
Affiliation:
Astronomy Department, University of Virginia Charlottesville, VA 22903, USA

Abstract

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We use a sample of 45 low-metallicity H II regions to determine the primordial helium abundance Yp. We have carefully investigated the physical effects which may make the He I line intensities deviate from their recombination values such as collisional and fluorescent enhancements, underlying He I stellar absorption and absorption by Galactic interstellar Na, I. By extrapolating the Y vs. O/H linear regression to O/H = 0, we obtain Yp = 0.245±0.002. Our Yp gives 0.06±0.01.

Type
II. Joint Discussions
Information
Highlights of Astronomy , Volume 11 , Issue 1: Highlights of Astronomy. As presented at the XXIIIrd General Assembly of the IAU (Part A), 1997 , 1998 , pp. 137 - 138
Copyright
Copyright © Kluwer 1998

References

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