Poster abstract details

The chemical evolution of interstellar sulfur and oxygen is widely believed to proceed in lockstep. As such, S and O abundance trends in both PNe and H II regions should mimic each other. Yet PN abundance studies in the MWG and other galaxies consistently show that PN S abundances are systematically below the corresponding level in H II regions for the same O abundance by a factor of 2 on average. In this paper we report on fresh attempts to identify causal parameters through numerous correlation tests of PN properties, an investigation of S depletion onto dust and molecules, consideration of S destruction via stellar nucleosynthesis, and tests for shortcomings of the current S ionization correction factor due to dielectronic recombination.