Figure 6

Lopsided outflow from the disc-magnetosphere boundary at a time corresponding to 203 rotation periods of the disc at the corotation radius ${\mathit{r}}_{\mathbf{cr}}$ , which is twice the star’s radius  ${\mathit{r}}_{\mathbf{\ast }}$ . The initial magnetic field, which is symmetric about $z=0$, is the sum of the stellar dipole (Eq. (8)) and the disc field (Eq. (9)), where the dipole and disc fields are parallel and equal in magnitude at $r=4.4r_{\ast }$ and $z=0$. The color background shows the density and the white lines the poloidal projection of the magnetic field lines. The arrows inside the disc (the orange region) are the poloidal velocity vectors, while the arrows external to the disc show the momentum density ρ v.