and $M_2$ (e.g., Cannizzo et al. 1988; Mineshige, Wood 1989). In principle, the easiest way to achieve a longer recurrence time would be to decrease ${\dot M}_{\rm T}$. While the value we have chosen here, ${\dot M}_{\rm T}$ = $3.16{\times}10^{16}$g s$^{-1}$, is plausible, it could be a factor of 10 smaller and still agrees with the observational constraints on, e.g. A0620–00.

Outburst Evolution
==================

Light Curves
------------

[2]{} [20pc]{} [Model light curves on the decline from the maximum along with the optical observations of A0620–00 (Webbink 1978 and private communication). The model optical maximum is defined as day zero. The data for A0620–00 is plotted 1.5 mag brighter than observed for clarity of presentation and their phase is set by assuming coincidence of the observed soft X-ray peak and the model optical maximum (see text). The model with both direct and indirect irradiation fits the observed optical light curve of A0620–00 with an assumed inclination of 60$^{\circ}$ and a distance of 400 pc.]{}

The optical light curves are computed by assuming that each disk annulus radiates as a black body at temperature $T_{\rm eff}(R,t)$ and summing the emission in the $V$ band over the annuli. The resultant model optical light 