Relative frequencies of Type Ia and Type II supernovae in the chemical evolution of the Galaxy, LMC and SMC

Abstract

The predicted nucleosynthesis products of Type Ia and Type II supernovae are combined with various parameter ratios and compared with the solar abundances of heavy elements and their isotopes, and also with the abundances of heavy elements in the LMC and SMC. Aided by a reasonable model of galactic chemical evolution, the ratio of the total numbers (of all time) of Type Ia to Type II supernovae that best reproduces the observed abundances is determined to be NIa/NII = 0.15 for the Galaxy, in agreement with current observations. For the MCs, however, this ratio is larger than that for the Galaxy, yielding NIa/NII = 0.2–0.3. We discuss several possible star formation history scenarios that may account for such an enhanced frequency of Type Ia supernovae in the MCs.