Most of the known transiting extrasolar planets orbit slowly rotating F, G or K stars. In here we report on the detection of a transiting planet orbiting the bright, rapidly rotating A5 star HD15082, recently made by SuperWASP. Time resolved spectroscopic observations taken during transit show a hump caused by the planet crossing the line profile. From the analysis of the spectra, we derive the radius of the planet and find that it is orbiting retrograde in respect to the spin of the star.

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... se of its small distance from an A5 star, this planet must be one of the hottest planets known, which makes it relatively easy to detect it in the IR. We thus tried to detect it using the TNG but did not succeed. Using direct imaging, we search for possible companions, and found one candidate. The importance of studying close-in planets of A-stars Studies of transiting extra-solar planets are of key importance for understanding the nature of planets outside our Solar System, because they allow to derive their mass, diameter and their density. The more than 100 transiting planets discovered up to now thus give us a wealth of information about the structure and evolution of extrasolar planets. However, almost all known transiting planets orbit F, G or K stars. Thus, only very little is known about the planets of A-stars. Studying such planet would however be very interesting, because planets of A-stars are exposed to a very high flux by the host star in the optical regime. By studying close-in planets of A-stars thus helps us to better understand the effects caused by the radiation of the host stars on the planets. However, important for the evaporation of the atmosphere of a planet is the amount of radiation which the planet receives shortward of the Ly-α line, not so much the radiation in the optical regime. Whether planets of A-stars also receive more photons in this wavelength regime is less obvious. In the classical view, A-stars do not have an outer convection zone and thus do not have a chromosphere, or a corona.