Name/Affiliation: Tereza Krejcova (Hamburg Observatory)
Exoplanetary systems containing hot Jupiters offer an unique opportunity to study the effects of mutual star-planet interaction. While the stellar high-energy radiation field is widely believed to influence the planetary atmosphere, e.g., by driving mass loss, it remains controversial whether close-in orbiting planets also influence the level or behavior of stellar activity through tidal or magnetic interaction. We present a study of changes of the chromospheric activity in stars with close-in exoplanets. In particular, we analyze various activity-sensitive spectral lines such as the Ca II H and K lines, H alpha, and the Ca II infrared triplet, examine their temporal variation and mutual relation, and study the relation to the planets. The special attention in this work will be paid to the transiting exoplanetary system HD 189733. It consists of a hot Jupiter orbiting an active K type star, which makes it a suitable object for study of the interaction in between the star and the planet.