The stability of magnetically threaded accretion disks

We study the non axisymmetric stability of a magnetically threaded accretion disks numerically in the (r, phi) plane with full hydrodynamics. The 3-D disk magnetosphere is solved in potential field approximation. We demonstrate the existence of a global instability which causes the initial surface mass-and magnetic flux density distribution to be redistributed on the rather short orbital timescale, i.e. the dynamical timescale. As long as the instability works a significant fraction of the disk mass is accreted to the central object. After the instability the surface density decreases exponentially with disk radius.