The observations of enhanced chromospheric activity on HD 179949 as well as on v And with the same periods as their close-in planets seem to indicate some kind of feedback from the planet to the star. We present a model, which is based on the propagation of Alfvén waves within the stellar wind flow relative to the planet and which can meet this restriction. In the solar system such a model is successfully used to explain the current system between Io and Jupiter.