Hd 147506b:: A supermassive planet in an eccentric orbit transiting a bright star

We report the discovery of a massive (M-p = 9.04 +/- 0.50 M-J) planet transiting the bright (V = 8.7) F8 star HD 147506, with an orbital period of 5.63341 +/- 0.00013 days and an eccentricity of e = 0.520 +/- 0.010. From the transit light curve we determine that the radius of the planet is R-p = 0.982(-0.105)(+0.038) R-J. HD 147506b (also coined HAT-P-2b) has a mass about 9 times the average mass of previously known transiting exoplanets and a density of rho(p) approximate to 12 g cm(-3), greater than that of rocky planets like the Earth. Its mass and radius are marginally consistent with theories of structure of massive giant planets composed of pure H and He, and accounting for them may require a large (greater than or similar to 100M(circle plus)) core. The high eccentricity causes a ninefold variation of insolation of the planet between peri-and apastron. Using follow-up photometry, we find that the center of transit is T-mid = 2,454,212.8559 +/- 0.0007 (HJD) and the transit duration is 0: 177 +/- 0.002 days.