What can stellar magnetic field tell us about exoplanetary systems ?

Séminaire IPAG de Rim Fares (St Andrews), jeudi 22 mai 2014 à 11h00, IPAG seminar room

Extrasolar planets at small orbital distances (hot Jupiters) interact with their hosting star in several ways : irradiation, gravitation, flow of particles and magnetic fields. The planet, embedded in the large-scale stellar magnetic field throughout its orbit, can influence the star in the form of induced photospheric activity, or by influencing the stellar magnetic field via tidal interactions. Studying the stellar magnetic field can give us insights on the interactions in these systems.

I will present my work on the study of the magnetic field of a sample of hot-Jupiter hosting stars. I will compare their magnetic properties to those of cool stars without hot-Jupiter companions. We observed the first large-scale magnetic cycle for a star other than the Sun. The magnetic field flips polarity every year. I will discuss the possible role of star-planet interactions on such a short cycle.

In addition to this observational aspect, I will discuss the effect the stellar magnetic field on the planet, planetary environment and planetary radio emission.