A large part of the exoplanets known today are in very close orbit around their star, allowing very intense interactions between the planets and the host star. An international collaboration, led by researchers from Department of Astrophysics-AIM Laboratory at CEA-Irfu, has shown that these planets in close orbits migrate rapidly, due to the combined effect of tidal forces and magnetic forces. This study provides essential elements for understanding the formation and evolution of star-planet systems.