The zoo of dwarf novae : illumination, evaporation and disc radius variation

Abstract

In the framework of the dwarf nova thermal-viscous disc instability model, we investigate the combined effects on the predicted dwarf nova lightcurves of irradiating the accretion disc and the secondary star and of evaporating the inner parts of the disc. We assume the standard values of viscosity. We confirm the suggestion by Warner (1998) that the large variety of observed outbursts' behaviour may result from the interplay of these three effects. We are able to reproduce light curves reminiscent of those of systems such as RZ LMi or EG Cnc. We can obtain long lasting outbursts, very similar to superoutbursts, without assuming the presence of a tidal instability.