Extrasolar Planets and Star-Planet Interaction

Exoplanets, i.e., planets orbiting the stars other than the Sun, can be studied across the whole electromagnetic spectrum. In the context of X-ray observations, two main areas are of interest. The first is exoplanets as the objects causing emission or absorption in X-rays; X-ray emission has been observed for several planets in the solar system, and observable X-ray absorption is expected especially for highly irradiated exoplanets with extended atmospheres. The second area is the field of star-planet interactions, where a star and a nearby planet interact through tides, magnetic fields, or accretion of the planetary atmosphere onto the host star, each of which may cause some observable effects in the X-ray emission originating from the host stars.