WASP-5b: a dense, very hot Jupiter transiting a 12th-mag Southern-hemisphere star

We report the discovery of WASP-5b, a Jupiter-mass planet orbiting a 12th-mag G-type star in the Southern hemisphere. The 1.6-d orbital period places WASP-5b in the class of very hot Jupiters and leads to a predicted equilibrium temperature of 1750K. WASP-5b is the densest of any known Jovian-mass planet, being a factor of 7 denser than TrES-4, which is subject to similar stellar insolation, and a factor of 3 denser than WASP-4b, which has a similar orbital period. We present transit photometry and radial velocity measurements of WASP-5 (= USNO-B10487-0799749), from which we derive the mass, radius and density of the planet: M_P = 1.58^+0.13_-0.08M_J,R_P = 1.090^+0.094_-0.058R_J and ρ_P = 1.22^+0.19_-0.24ρ_J. The orbital period is P = 1.6284296^+0.0000048_-0.0000037d and the mid-transit epoch is T_C(HJD) = 2454375.62466^+0.00026_-0.00025.