WASP-19b: THE SHORTEST PERIOD TRANSITING EXOPLANET YET DISCOVERED

We report on the discovery of a new extremely short period transiting extrasolar planet, WASP-19b. The planet has mass M(pl) = 1.15 +/- 0.08 M(J), radius R(pl) = 1.31 +/- 0.06 R(J), and orbital period P = 0.7888399 +/- 0.0000008 days. Through spectroscopic analysis, we determine the host star to be a slightly super-solar metallicity ([M/H] = 0.1 +/- 0.1 dex) G-dwarf with T(eff) = 5500 +/- 100 K. In addition, we detect periodic, sinusoidal flux variations in the light curve which are used to derive a rotation period for the star of P(rot) = 10.5 +/- 0.2 days. The relatively short stellar rotation period suggests that either WASP-19 is somewhat young (similar to 600 Myr old) or tidal interactions between the two bodies have caused the planet to spiral inward over its lifetime resulting in the spin-up of the star. Due to the detection of the rotation period, this system has the potential to place strong constraints on the stellar tidal quality factor, Q(s)('), if a more precise age is determined.