Chemodynamical model of the galaxy: Abundance gradients predicted for H II regions and planetary nebulae

We present a chemodynamical evolution model of the Galaxy to determine chemical abundance gradients of different stellar populations. From this model we have determined the abundance gradients expected for H II regions, as well as for planetary nebulae of different ages and different kinematical properties. We have compared the model predicted gradients with those derived from planetary nebulae (PNs) of types I, II, and III. From this comparison we conclude that only about half of the stars evolving toward the white dwarf stage produce PNs and that the less massive stars are less likely to produce PNs. Other arguments supporting the previous conclusions are presented.