Galactic chemical evolution: The intermediate mass elements

Nucleosynthesis in the intermediate mass range (carbon through nickel) has been calculated for a grid of stellar masses between 10 and 40 M_(.) for solar metallicity, and 12 and 75 M_(.) for zero metallicity, with a total of 26 stars evolved to the presupernova state. Explosions have been simulated in 13 of these and the final nucleosynthetic yields, including the v-process, are determined. Except for the products of the neutrino process (fluorine and boron), the presupernova abundances of isotopes lighter than about A=40, closely resemble the final yields. These results, when incorporated into a model for galactic chemical evolution that includes contributions from lower mass stars and Type Ia supernovae, give present day abundances that are in good agreement with those observed in the solar system when a particular choice is made for the ¹²C( alpha , gamma )¹⁶O reaction rate.