A NEW MODEL OF THE STRUCTURE OF SPIRAL GALAXIES BASED ON PROPAGATING STAR-FORMATION .1. THE GALACTIC STAR-FORMATION RATE AND SCHMIDT LAW

We have constructed a new model for galactic structure based on the principles of propagating star formation. Unlike earlier simulations using this mechanism, it represents the galactic molecular clouds as distinct entities which move, interacting with one another through collisions, in a constant potential held. This allows us to superimpose on the propagation a spiral density wave and include more realistic dynamics for the interstellar medium. Using as input parameters values appropriate for our own Galaxy, we are able to reproduce the Galactic star formation rate to within the uncertainties of our model. Furthermore, we predict a Schmidt-type law for the integrated star formation rate which is in excellent agreement with observations.