  The rotation period of some planet-hosting stars appears to be in close
commensurability with the orbital period of their close-by planets. A model is
proposed to interpret such a phenomenon based on the excitation of resonant
oscillations in the interior magnetic field of the star by a component of the
tidal potential with a very low frequency in the reference frame rotating with
the star. A magnetic flux tube located in the overshoot layer of the star is
assumed to study the excitation of the resonant oscillations in the
magnetostrophic regime. The model considers a planet on a circular oblique
orbit and the growth timescale of the oscillations is estimated. To keep the
system in resonance with the exciting potential, in spite of the variations in
the magnetic field or tidal frequency, a self-regulating mechanism is proposed.
The model is applied to ten systems and proves capable of accounting for the
observed close commensurability in eight of them by assuming a magnetic field
between $10^{2}$ and $10^{4}$ G. Systems with low-mass distant planets, such as
AU Mic and HAT-P-11, cannot be interpreted by the proposed model. Consequences
for the spin-orbit evolution of the systems, including dynamical tides and
gyrochronology of planet-hosting stars, are discussed together with the effects
on the chromospheric features produced by star-planet magnetic interactions.
