Stellar Mixing from Galactic and Magellanic Cloud Planetary Nebulae Abundances

Abstract

The mixing and nucleosynthetic processes which occur in the main-sequence and red giant stages of evolution and which can affect measured PN abundances are discussed. It is suggested that samples of planetary nebulae contain a sufficient range of progenitor stars' initial metallicities, angular momenta, binarity, etc. so as to explain the large scatter always seen in abundance diagrams for PN samples. CNO abundances in the Galactic disk and in the Magellanic Clouds are reviewed. New results for nebular abundances and central star properties in the Clouds are given. The current red giant population in the Clouds mix out more 12C per star than their Galactic disk counterparts.