Magnetic star-disk interaction in classical T Tauri systems

We simulate the impact of a dipolar stellar magnetic field rooted in a classical T Tauri star on the accretion disk and the halo above using a 2.5D finite difference code. The gas is assumed resistive, and inside the disk accretion is driven by a Shakura-Sunyaev-type eddy viscosity. The rotational shear between the star and the Keplerian disk causes the magnetic field to be wound up and stretched outwards, away from the star. Part of the field lines open and an outflow is launched. Direct disk disruption by the Lorentz force only occurs for sufficient field strength. For our model system with a solar-mass central star, an accretion rate of 10^-7M⊙/a, and a viscosity parameter α_SS=0.01, a field strength of 1 kG, measured at the poles on the surface of the star, was found insufficient for disk disruption.