PN Abundances in Different Galactic Systems

Abstract

Developments in the measurement of abundances in planetary nebulae since IAU Symposium 131 are reviewed. Present uncertainties and outstanding problems in the interpretation of emission-line measurements are discussed. Results for different samples of PN are reviewed, in terms of the galactic site. Results for the Galactic disk, Galactic Bulge, Galactic Halo, LMC & SMC, Fornax Dwarf galaxy and M31 are discussed. Attention is drawn to the importance of Magellanic Cloud samples for testing dredge-up theory, and to the strong variation of PN C/O ratios with the local site's metallicity and age. New results for carbon in Cloud PNs are presented. Important problems in the interpretation of the metallicity of Bulge PNs are highlighted. Attention is drawn to the idea that metal-rich stellar populations do not produce PNs, such stars leaving the lower AGB early.