HST/STIS UV spectra of Galactic PNe

We carried out a snapshot survey of compact Galactic planetary nebulae (PNe) to acquire their UV spectra, with the aim of determining their gas-phase carbon abundances. Planetary nebulae are major cosmic recyclers, and their carbon content is essential to constrain the models of Asymptotic Giant Branch (AGB) evolution. There is an observed correlation between the gas and dust components of PNe in the Magellanic Clouds, but such a relation cannot yet be established for Galactic PNe given the lack of gas-phase carbon abundances of PNe whose dust composition is known. Our program measured carbon abundances for a set of compact Galactic PNe previously imaged with the HST cameras, whose dust content is known from IR/Spitzer spectral analysis, and whose ground-based optical spectra are also available from ancillary data sets. We studied carbon abundances of Galactic PNe in the framework of the yields from AGB evolution, especially with recent models that include dust evolution. Finally, compared the results of the Galactic study with similar studies based on LMC and SMC PNe, to gain insight of AGB evolution at different metallicities.