PN G000.2+06.1 and PN G002.3+02.2: Two New Type I Planetary Nebulae in the Galactic Bulge

Abstract

We confirm the planetary nebula nature of two sources: PN G000.2+06.1 and PN G002.3+02.2, previously identified by Terzan in a photometric survey toward the Galactic center as objects possibly belonging to this class. Optical images taken in Hα reveal the extended morphology of the nebulae, while spectroscopic observations allow us to determine their line intensities and physical parameters (electron density and temperature), as well as their ionic and elemental abundances. Their low surface brightness and large apparent size, together with the lack of infrared emission, suggest their identification as well-evolved planetary nebulae belonging to the old stellar population of the bulge. However, both planetary nebulae show high N/O ratios and He abundances, similar to those observed in type I disk planetary nebulae, usually associated with young, massive progenitor stars. The implications of our findings in the context of the study of chemical abundances in Galactic bulge planetary nebulae are discussed.