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Paper: Some Implications of Galactic Abundance Gradients Derived from H II Regions and Planetary Nebulae
Volume: 147, Abundance Profiles: Diagnostic Tools for Galaxy History
Page: 88
Authors: Peimbert, Manuel; Carigi, Leticia
Abstract: By comparing observed abundance gradients with those predicted by a chemodynamical model of the Galaxy, the following results are obtained: there is a deficiency of O/H poor PNe in the solar vicinity implying that only a fraction of intermediate mass stars produces PNe; a similar result is obtained from the observed abundance distribution of Ne/H, S/H and Ar/H; the age distributions of the stellar progenitors of type II and type III PNe show a substantial overlap, but the average age of the progenitors of type III PNe is larger than that of the progenitors of type II PNe; the S/H and the Ar/H gradients of type I PNe and H\,Ii regions are similar; the flatter O/H gradient of type I PNe relative to that of H\,Ii regions is probably due to the effect of temperature fluctuations on the abundance determinations; the similarity of the abundance gradients derived from H ii regions and PNe implies that transient phenomena are not important in shaping the present day H ii gradients.
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