Chemical abundances in LMC and SMC planetary nebulae

Abundances of He, N, O, and Ne are calculated for 29 faint planetary nebulae in the LMC and SMC from spectrophotometry obtained by Boroson and Liebert. When the results are combined with abundances from Aller and Czyzak's galactic planetary sample, the following conclusions are drawn: (1) O and Ne in planetaries remains generally unchanged throughout the evolution of the progenitor; (2) O and Ne abundances are indicators of progenitor metallicity; (3) Significant amounts of N are produced during evolution of intermediate mass stars, and (4) H production in intermediate mass stars over time can explain the current interstellar abundance of N in the LMC but not in the SMC.