Vertical convection in turbulent accretion disks and light curves of the X-ray nova A0620-00 1975 outburst

The model of a nonstationary alpha-disk with allowance made for the irradiation and vertical convection in the outer accretion disk, where hydrogen is partially ionized, is considered. Allowance for the energy release through turbulent viscosity is shown to be important in the mixing-length convection theory in accretion disks. This model has been used to explain the optical and X-ray light curves of the X-ray nova A0620-00. The turbulent viscosity parameter of the accretion disk has been estimated, alpha = 0.5-0.6, to explain the luminosity decay rate on the descending branch of the X-ray light curve for the A0620-00 1975 outburst. The secondary luminosity maximum on the light curves is explained by assuming an additional injection of matter into the accretion disk from the optical companion.