Disc Disruption and Accretion Curtains
The intermediate polars, some X-ray binary pulsars and the accreting millisecond pulsars have magnetic primary stars accreting from a partially disrupted disc via an inner magnetically channelled curtain flow. The stellar magnetic field and the associated magnetosphere interact with the disc in a way which is affected by the strength of its magnetic diffusivity. For sufficiently large η values, the stellar poloidal field lines remain closed and linked to the disc. For smaller values of η field line opening can occur and wind flows can result from the disc and the primary star. Angular momentum can be transported in a variety of ways.
Field lines inside the corotation radius tend to remain closed and the disc becomes disrupted as a result of vertical expansion due to magnetic heating. Expanding material can be accelerated through a sonic point and then flow through a magnetically channelled curtain region to accrete on to the star through a narrow shock region. A detailed study of disc disruption and the curtain flow is presented here.