  Hot Jupiters (HJs) are massive gaseous planets orbiting close to their host
stars. Due to their physical characteristics and proximity to the central star,
HJs are the natural laboratories to study the process of star-planet
interaction (SPI). Phenomena related to SPI may include the inflation and the
evaporation of planetary atmospheres, the formation of cometary tails and bow
shocks and magnetospheric interaction between the magnetic field of the planet
and that of the star. Several works suggest that some systems show enhanced
stellar activity in phase with the planetary rotation period. In this work, we
use a 3D magneto-hydrodynamic model that describes a system composed of a star
and an HJ and that includes the corresponding planetary and stellar winds. The
aim is to investigate whether the material evaporating from the planet
interacts with the stellar extended corona, and generates observable features.
Our simulation shows that, in some conditions, the planetary wind expands and
propagates mainly along the planetary orbit. Moreover, part of the planetary
wind collides with the stellar wind and a fraction of the planet's outflow is
funnelled by the stellar magnetic field and hits the stellar surface. In both
events, the material is heated up to temperatures of a few MK by a shock. These
phenomena could manifest in the form of enhanced stellar activity at some
orbital phases of the planet.
