WASP-41b: A Transiting Hot Jupiter Planet Orbiting a Magnetically Active G8V Star

ABSTRACT.We report the discovery of a transiting planet with an orbital period of 3.05 days orbiting the star TYC 7247-587-1. The star, WASP-41, is a moderately bright G8 VV star (V = 11.6V=11.6) with a metallicity close to solar ([Fe/H] = -0.08 ± 0.09[Fe/H]=-0.08±0.09). The star shows evidence of moderate chromospheric activity, both from emission in the cores of the Ca ii H and K ines and photometric variability with a period of 18.4 days and an amplitude of about 1%. We use a new method to show quantitatively that this periodic signal has a low false-alarm probability. The rotation period of the star implies a gyrochronological age for WASP-41 of 1.8 Gyr with an error of about 15%. We have used a combined analysis of the available photometric and spectroscopic data to derive the mass and radius of the planet (0.92 ± 0.06 MJup0.92±0.06  MJup, 1.20 ± 0.06 RJup1.20±0.06  RJup). Further observations of WASP-41 can be used to explore the connections between the properties of hot Jupiter planets and the leve...