Magnetohydrodynamic Simulations of Stellar Magnetosphere–Accretion Disk Interaction

The magnetohydrodynamic evolution of the interaction region between the inner edge of an accretion disk and the magnetosphere of the central object is studied by means of time-dependent numerical simulations. The simulations assume the disk is adiabatic, is axisymmetric, has nonzero resistivity, and is initially in Keplerian rotation. The magnetosphere is assumed to be initially in magnetostatic equilibrium, corotating with the central star, and threaded by one of three different initial magnetic field topologies: (1) a pure dipole field, which also threads the disk continuously everywhere; (2) a dipole field excluded from the disk by surface currents; and (3) a dipole field continuously threading a disk superposed with a uniform axial magnetic field. A number of exploratory simulations are performed by varying the field strength, the disk density and inner radius, the magnitude of the resistivity, and the stellar rotation rate. These simulations are designed as an initial study of the magnetohydrodynamics of the interaction region.

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