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Seven problems related to the determination of the primordial helium abundance

Manuel Peimbert·Antonio Peimbert·Valentina Luridiana·Maria Teresa Ruiz
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Abstract

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.

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Manuel Peimbert, Antonio Peimbert, Valentina Luridiana, Maria Teresa Ruiz. 2002-11-22. Seven problems related to the determination of the primordial helium abundance. https://arxiv.org/abs/astro-ph/0211497

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