On The Rate of Novae in Galaxies of Different Types

Using a population-synthesis code, we calculate the expected nova rate in stellar systems with di erent star formation histories for a variety of input parameters concerning the initial binary population. We show that the current nova rate in a galaxy is determined by the galaxys star formation history. We show that in irregular and spiral galaxies, the currently observed nova rates are determined mainly by the present disk star formation rate, while in elliptical galaxies the rate depends mainly on the mass of the galaxy. This o ers an explanation for the suspected di erences in the observed nova rates per unit of K luminosity in di erent galaxies. The di erences between bulge and disk novae in the Galaxy are probably also related to the respective ages of the parent populations.