Context. Signatures of chromospheric activity enhancement have been found for a dozen stars, pointing to a possible star-planet interaction. Nevertheless in the coronal activity regime, there is no conclusive observational evidence of such an interaction. Does star-planet interaction manifest itself only for a few particular cases, without having a major effect on stars with planets in general? Aims. We aim to add additional observational constraints to support or reject the major effects of star-planet interactions in stellar activity, based on Ca II chromospheric emission flux. Methods. We performed a statistical analysis of Ca II emission flux of stars with planets, as well as a comparison between Ca II and X-ray emission fluxes, searching for dependencies on planetary parameters. Results. In the present sample of stars with planets, there are no significant correlations between chromospheric activity indicator log(R HK ) and planetary parameters. Furthermore, the distribution of the chromospheric activity indicator for stars without planets is indistinguishable from the one with planets.

Using X-ray observation we have obtained the deprojected gas density and temperature profiles for a sample of cluster of galaxies. We show that cool-core clusters, which are expected to be the largest relaxed structures in the universe, have central steep mass density profiles, similar to the cold dark matter density profiles resulting from cosmological N-body simulation. We will present detailed results for two clusters, Abell 85 and 586.