Planetary nebula carbon yields and the chemical evolution of the Galactic disc

Two sets of observational carbon stellar yields for low- and-intermediate mass stars are computed based on planetary nebula abundances derived from C iilambda4267 and C iiilambdalambda1906 + 1909 lines, respectively. These observational yields are assumed in chemical evolution models for the solar vicinity and the Galactic disc. C/O values observed in stars in the solar vicinity and Galactic H ii regions are compared with those predicted by chemical evolution models for the Galaxy. It is concluded that the C yields derived from permitted lines are in better agreement with the observational constraints than are those derived from forbidden lines.