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Planetary Nebulae and the Pregalactic Helium Abundance
Published online by Cambridge University Press: 19 July 2016
Extract
Recent work has emphasized the determination of the pregalactic helium abundance by mass Yp and the slope ΔY/ΔZ based on the chemical composition of both galactic and extragalactic H II regions (Pagel, 1987; Pagel et al., 1986).
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- II. Nebular Properties
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- Copyright © Kluwer 1989
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