Abstract
A self-consistent analytical chemical evolution model is developed for the Galactic halo and the disk in the solar neighbourhood using Hartwick's (1976) modified Simple model for the halo and Clayton's analytical inflow formalism for the disk (including a modest initial enrichment from the halo), both formalisms being modified to allow for a time delay between the production of "prompt" elements such as oxygen, α-elements, r-process elements and one component of iron and that of "delayed elements" such as s-process products (from intermediate-mass stars) and another component of iron (from Type Ia supernovae). The model conforms fairly well to traditional constraints like the behaviour of star formation rates and the G dwarf problem, and its predictions also agree as well as can be expected in view of uncertainties in the data with observed trends in Ba relative to Eu and in O and α elements relative to iron, assuming constant yields throughout, which suggests that enrichment as a function of time is indeed an important effect and that the s-process is "primary". The model is also used as a test of some ideas concerning the origin of abundance gradients.
