Departamento de Astronomia, IAG/USP, CP 3386, 01060-970 São Paulo, Brasil e-mail: email@example.com; firstname.lastname@example.org
Corresponding author: R. D. D. Costa, email@example.com
Accepted: 24 September 2001
In this work we report spectrophotometric observations of a planetary nebula sample towards the galactic bulge. A total of 45 PNe was observed and their physical parameters (electron density and temperature) were derived. Ionic abundances were calculated using a three-level atom model and abundances were derived through ionisation correction factors. Results show low abundance objects at high galactic latitudes, indicating a possible vertical gradient inside the bulge. A few objects with low N/O ratio were found, which could have originated from old, low mass progenitors.
Key words: ISM: planetary nebulae: general / Galaxy: bulge / techniques: spectroscopic
Based on observations made at the European Southern Observatory (Chile) and Laboratório Nacional de Astrofísica (Brasil).
© ESO, 2001