Angles and vectors used in Section 4: |$\boldsymbol{e}_x$|⁠, |$\boldsymbol{e}_y$|⁠, |$\boldsymbol{e}_z$| are the principal axes of the star effective inertia tensor |$I_{\rm eff}^{ij}$|⁠, β is the angle between the Z-axis and the star's magnetic moment direction, ϑ is the precession angle and χ is the inclination angle.