The Effects of Mass and Metallicity upon PN Formation

Extract

We construct a parameterized function which describes the possible dependence of planetary nebulae formation upon metal abundance and stellar mass. Data on galaxies in the local group compared with predictions made from the parameterized function indicate that heavy element abundance is the principal agent influencing the formation of planetary nebulae; stars which are rich in heavy elements are the progenitors of planetary nebulae. Our analysis, when compared with the observations, argues for a modest degree of pre-enrichment in a few of the sample galaxies. The heavy element dependence of planetary nebulae formation also accounts for the deficit of planetary nebulae in the nuclei of NGC 221 and NGC 224, and in the bulge of our galaxy.