We report the discovery of a transiting planet with an orbital period of 3.05 d orbiting the star TYC 7247-587-1 .
The star , WASP-41 , is a moderately bright G8 V star ( V=11.6 ) with a metallicity close to solar ( [ Fe/H ] = -0.08 \pm 0.09 ) .
The star shows evidence of moderate chromospheric activity , both from emission in the cores of the Ca II H and K lines and photometric variability with a period of 18.4 d 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 \pm 0.06 M _ { Jup } , 1.20 \pm 0.06 R _ { Jup } ) .
Further observations of WASP-41 can be used to explore the connections between the properties of hot Jupiter planets and the level of chromospheric activity in their host stars .