  Planets in close-in orbit interact with the magnetized wind of their hosting
star. This magnetic interaction was proposed to be a source for enhanced
emissions in the chromosphere of the star, and to participate in setting the
migration time-scale of the close-in planet. The efficiency of the magnetic
interaction is know to depend on the magnetic properties of the host star, of
the planet, and on the magnetic topology of the interaction. We use a global,
three-dimensional numerical model of close-in star planet systems, based on the
magnetohydrodynamics approximation, to compute a grid of simulations for
varying properties of the orbiting planet. We propose a simple parametrization
of the magnetic torque that applies to the planet, and of the energy flux
generated by the interaction. The dependancy upon the planet properties and the
wind properties are clearly identified in the derived scaling laws, which can
be used in secular evolution codes to take into account the effect of magnetic
interactions in planet migration. They can also be used to estimate a potential
magnetic source of enhanced emissions in observed close-in star-planet systems,
in order to constrain observationally possible exoplanetary magnetic fields.
