Modeling the Photopolarimetric Variability of AA Tau
  We present Monte Carlo scattered light models of a warped disk that reproduce the observed photopolarimetric variability of the classical T Tauri star AA Tau. For a system inclination of 75 deg and using an analytic description for a warped inner disk, we find that the shape and amplitude of the photopolarimetric variability are reproduced with a warp which occults the star, located at 0.07 au, amplitude 0.016 au, extending over radial and azimuthal ranges 0.0084 au and 145 deg. We also show a time sequence of high spatial resolution scattered light images, showing a dark shadow cast by the warp sweeping round the disk. Using a modified smooth particle hydrodynamics code, we find that a stellar dipole magnetic field of strength 5.2 kG, inclined at 30 deg to the stellar rotation axis can reproduce the required disk warping to explain AA Tau's photopolarimetric variability. 
Mark O'Sullivan, Michael Truss, Christina Walker, Kenneth Wood, Owen   Matthews, Barbara Whitney & J.E. Bjorkman