Morphology of the Interaction Between the Stream and Cool Accretion Disk in a Semi-detached Binary Systems

TL;DR

This study investigates the interaction between the accretion stream and cool disks in close binary systems, revealing a shockless interaction and identifying a hot zone beyond the disk through 3D modeling.

Contribution

It provides the first 3D simulations of stream-disk interaction in cool accretion disks, showing shockless flow and the formation of a hot line beyond the disk.

Findings

Interaction remains shockless at low disk temperatures.

A hot line forms beyond the disk due to halo-stream interaction.

Flow pattern consistent with previous hot disk studies.

Abstract

We analyze heating and cooling processes in accretion disks in binaries. For realistic parameters of the accretion disks in close binaries (with accretion rates from 1e-12 to 1e-7 Msun/year and \alpha from 0.1 to 0.01), the gas temperature in the outer parts of the disk is from 1e4 to 1e6 K. Our previous gas-dynamical studies of mass transfer in close binaries indicate that, for hot disks (with temperatures for the outer parts of the disk of several hundred thousand K), the interaction between the stream from the inner Lagrange point and the disk is shockless. To study the morphology of the interaction between the stream and a cool accretion disk, we carried out three-dimensional modeling of the flow structure in a binary for the case when the gas temperature in the outer parts of the forming disk does not exceed 13600 K. The flow pattern indicates that the interaction is again shockless. The computations provide evidence that, as is the case for hot disks, the zone of enhanced energy release (the "hot line") is located beyond the disk, and originates due to the interaction between the circum-disk halo and the stream.