W. J. Maciel - Abstract #45RADIAL ABUNDANCE GRADIENTS AND THE SIMPLE MODEL FOR THE CHEMICAL EVOLUTION OF THE GALAXYW. J. Maciel Astrophys. Space Sci. 196, 23-28 (1992) The oxygen abundance gradient relative to hydrogen is considered, as derived from galactic HII regions and type II planetary nebulae. The so-called `simple' model for the chemical evolution of the Galaxy is shown to explain well the observed gradients, provided some reasonable assumptions are made regarding the gas distribution in the galactic disk. |