ИСТИНА

We described phenomenon of X-ray Novae with a model of non-stationary accretion $alpha$-disk with regard of illumination and vertical convection in outer region of the disk. We extended commonly used model of disk vertical structure by adding viscous turbulent energy generation into mixing length theory. This model was used to simulate both optical and X-ray light curves of the 1975 outburst of X-ray Nova A0620-00. We fitted these light curves with observations and estimated turbulent $alpha$-parameter of the accretion disk with values $0.5 \div 0.6$.