HD 147506b : A SUPERMASSIVE PLANET IN AN ECCENTRIC ORBIT TRANSITING A BRIGHT STAR

We report the discovery of a massive (M sub(P) = 0.04 plus or minus 0.50 M sub(J)) planet transiting the bright (V = 8.7) F8 star HD 147506, with an orbital period of 5.63341 plus or minus 0.00013 days and an eccentricity of e = 0.520 plus or minus 0.010. From the transit light curve we determine that the radius of the planet is R sub(P) = 0.982 super(+) sub(-) super(0) sub(0) super(.) sub(.) super(0) sub(1) super(3) sub(0) super(8) sub(5) R sub(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 P sub(P) approximately 12 g cm super(-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 equal to 100 M sub(m)) 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 [unk] = 2, 454, 212.8559 plus or minus 0.0007 (HJD) and the transit duration is 0.177 plus or minus 0.002 days.