Improving the determination of chemical abundances in planetary nebulae
  Planetary nebulae are the products of the evolution of low and intermediate
mass stars. The chemical property studies of these objects give important
information about the elemental abundances as He, O, Ne, Ar, S and their
modifications associated with the evolution of the progenitor stars. The
determination of accurate abundances in planetary nebulae is important from the
perspective of the stellar evolution as well as the formation and chemical
evolution of galaxies. Recently, new HeI emissivities and ionization correction
factors (ICFs) were published in the literature. In this work, these new
parameters are used in a code for the determination of chemical abundances in
photoionized nebulae. This code is used for the recompilation of the chemical
abundances of planetary nebulae from the Galactic bulge observed previously by
our group and also for the determination of new chemical abundances of a sample
of planetary nebulae located near the Galactic centre. The new emissivities and
ICFs slightly modified the elemental abundances of He, N, O, Ar and Ne. On the
other hand, S abundances are higher than previous determinations. The new ICFs
can contribute to solve partially the sulphur anomaly.
