On Possible Nature of Pre-eclipse Dips in Light Curves of Semi-detached Systems with Steady-state Disks

Abstract

In order to explain pre-eclipse dips at phases ∼0.7 in light curves of cataclysmic variables, the hypothesis of the thickening at the outer edge of the accretion disk is usually used. Shock-free nature of the interaction between the stream and the steady-state disk in the stationary solution poses the question on the cause of the of matter presence at significant height above the accretion disk in systems of this type. The results of 3D modeling have shown that in the absence of direct collision between the stream and the disk the formation of thickening of the halo above the disk is also possible. In the framework of the hot line model the significant part of the matter gets the acceleration in vertical direction. Gas movement in the vertical direction together with its movement along the outer edge of the disk leads to the gradual increase of the near-disk halo width. Maximum of the calculated thickening located above the outer part of the disk corresponds to the ∼0.7 phase that is in agreement with the observed values for cataclysmic variables with steady-state disks. This fact confirms the hot line model suggested earlier for description of the flow structure in semi-detached binaries and gives new opportunities for the interpretation of the light curves of such systems.