ACCRETION DISK BOUNDARY-LAYERS IN CLASSICAL T-TAURI STARS

The dynamical and thermal structure of an opaque boundary layer, conne cting a classical T Tauri star (CTTS: M = 1 M., R* = 4.3 R., T-eff = 5000 K) with its accretion disk (M = 10(-7) M./yr), has been computed, including particularly the effect of a turbulence-driven global heat transport. The inner boundary has been shifted deeper and deeper into the star's envelope in order to determine how this affects the amount of angular momentum transfer. If the optical depth in the star's envel ope, where the disk meets the star, exceeds in our model example great er than or similar to 10, then there is an energy flux from the star i nto the boundary layer. For even larger (greater than or similar to 30 ) optical depths this outward flux approaches the star's radiation flu x and the boundary layer becomes a ''hot'' one. The angular momentum p arameter E alone does not determine the solution uniquely. For a given E there are, sometimes, two solutions. An argument is given why E app roximate to 1.