Illustration for the structure of the system for the magnetic interpretation. The spinning subdwarf (in blue) generates a dipolar magnetic field around it, which is not necessarily aligned with the spin. The wind material in the innermost region, within Kepler radius R_K, has no centrifugal support and can fall freely back onto the star, thus forming a dynamical magnetosphere. The material between the Keplerian co-rotation radius R_K and the Alfvén radius R_A has centrifugal support. It cannot fall back onto the star, thus forming a much denser rigidly rotating magnetosphere. The illustration is inspired by Petit et al. (2013).