Recent spectroscopic measurements of transiting extrasolar planets revealed features of the planet’s atmospheres. Other photometric measurements were used to perform spot modelling on host stars. The missing link is the solar wind and its interaction with the planet. This is an important factor to understand the evolution of the planet and its habitability. We present new methods to investigate the solar wind and coronal activity of exoplanetary host-stars. We probe our theories on spectral transit observations of HD209458 as well as simulated transits on the sun. CoRoT-2b and CoRoT-4b as templates of planets around active stars will be investigated for signatures of coronal activity. Future mission, like the WSO-UV or spectroscopic measurements in the UV performed by the HST will bring us new insights on the solar wind activity of exoplanet host-stars. Poster
