THE CHEMICAL EVOLUTION OF GALAXIES

The chemical evolution of galaxies is discussed starting with the simp le box model. It is shown that this model with the additional assumpti on of metal-rich outflow provides a first useful insight into the chem ical evolution of different stellar populations. More detailed models of galactic nucleosynthesis are then investigated which take into acco unt galactic dynamics, non-instantaneous recycling and incomplete mixi ng. The implications of non-instantaneous recycling on the evolution o f the element abundances in the galactic halo are discussed and constr aints on the evolutionary timescales of the halo are derived. Finally a model for the formation of the galactic halo is presented which take s into account local enrichment and incomplete mixing between differen t gas phases.