We report that a Jupiter-mass planet , WASP-7b , transits the V = 9.5 star HD 197286 every 4.95 d. This is the brightest discovery from the WASP-South transit survey and the brightest transiting-exoplanet system in the Southern hemisphere .
WASP-7b is among the densest of the known Jupiter-mass planets , suggesting that it has a massive core .
The planet mass is 0.96 ^ { +0.12 } _ { -0.18 } M _ { Jup } , the radius 0.915 ^ { +0.046 } _ { -0.040 } R _ { Jup } and the density 1.26 ^ { +0.25 } _ { -0.21 } \rho _ { Jup } .