Chemo-spectrophotometric evolution of spiral galaxies: I. The model and the Milky Way

The chemical and spectro-photometric evolution of spiral galaxies is investigated with detailed models, making use of up-to-date ingredients (like metallicity dependent stellar properties) and a prescription for the star formation rate (SFR) justified both empirically and theoretically. As a first application, the model is used to describe the evolution of the Milky Way. The role of the adopted scheme of disk formation (``inside-out'') in shaping the various chemical and colour profiles is investigated, as well as the role of extinction. It is shown that the solar neighborhood does not evolve as the Milky Way as a whole and that one-zone models with a non-linear SFR prescription cannot be used to study the evolution of our Galaxy. Our model average SFR is shown to match well observations of external spirals.