Alfvénic heating of accretion disks

In this work, we investigate the eects of heating generated by nonlinear and turbulent damping of Alfv en waves. Our results are a function of two parameters: f = v=vA, which is a measure of the degree of turbulence, and F = $= i, which is the average frequency of the waves ( v, vA and $ are the amplitude, velocity and frequency of the Alfv en waves, respectively, and i is the ion cyclotron frequency). Only a small portion of the disk is studied, ranging from 0.1 AU to 1.4 AU. We nd that, when compared with the heating generated by viscous dissipation, the Alfv enic heating is important for R > 0:5 AU. An increase in temperature occurs, which causes an increase in the degree of ionization of the system. When irradiation from the central star is taken into account the increase in temperature is much more signican t. Due to Alfv enic heating, the inuence of the magnetorotational instability extends to a greater part of the protostellar accretion disk.