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R.B.C. Henry (U. Oklahoma), K.B. Kwitter (Williams College)
This paper arose out of a project designed to study carbon abundances in a sample of planetary nebulae representing a broad range in progenitor mass and metallicity. We collect abundances of He, C, N, O, and Ne determined for the entire sample and compare them with theoretical predictions of planetary nebula abundances from a grid of intermediate mass star models. We find very good agreement between observations and theory, lending strong support to our current understanding of nucleosynthesis in stars below 8 M\odot in birth mass. In particular, carbon and nitrogen abundance patterns are consistent with the occurrence of hot-bottom burning in stars above roughly 3.5 M\odot, a process which converts much of 12C into 14N during the AGB phase of evolution. This agreement between observations and theory also supports the validity of published stellar yields of carbon and nitrogen in the study of the abundance evolution of these elements. We gratefully acknowledge support from NASA (NAG 5-2389) and NSF (AST-9819123).
The author(s) of this abstract have provided an email address for comments about the abstract: henry@mail.nhn.ou.edu