Secular evolution of a star–planet system formed by a fast-rotating K star (M_⋆ = 0.8 M_⊙,  P_rot,ini = 1.4 days) orbited by a magnetized hot Neptune (M_p = 0.1 M_Jup,  a_ini = 0.035 AU) for two different values of the planetary magnetic field: B_p = {1, 10} G (in dashed and solid line, respectively). The thick curves correspond to our reference case discussed in Sect. 3.1.1. Top panel: semi-major axis (solid lines) and co-rotation radius of the star (black dashed lines). Wind braking + tides are shown in shades of red; wind braking + tides + magnetic effects are shown in shades of blue. The gray bands on the left correspond to the disk-locking phase. Bottom panel: tidal (shades of red) and magnetic (shades of blue) torques in the case of evolution with all the combined interactions. The white square corresponds to the ZAMS and the red circles to the crossing of the dynamical tide excitation limit by the planet.