An overabundance of oxygen in planetary nebulae of the solar
  neighborhood
  We study the oxygen abundance in five H II regions and seven planetary
nebulae (PNe) located within 2 kpc from the Sun that have available spectra of
high quality. Our analysis uses a similar procedure and the same atomic data to
derive abundances in all the objects. The results calculated with collisionally
excited lines for the H II regions indicate that the local interstellar medium
is very homogeneous, with 12+log(O/H)=8.45-8.54. As for the PNe, six out of
seven show significantly higher abundances: 12+log(O/H)=8.65-8.80. This
overabundance of oxygen in PNe also holds when we consider the abundances
implied by recombination lines.
