Figure 1

Slowly/rapidly rotating stars. Schematic profiles of the midplane angular velocity of the plasma for the case of a slowly rotating star (left-hand panel) and a rapidly rotating star (right-hand panel) which is in the propeller regime. Here, ${\mathrm{\Omega }}_{\ast }$ is the angular rotation rate of the star, ${\mathrm{\Omega }}_K$ is the Keplerian rotation rate of the disc, $r_{\ast }$ is the star’s radius, $r_{\mathrm{m}}$ is the radius of the magnetosphere, and $r_{\mathrm{cr}}$ is the co-rotation radius.