[en] planetary systems ; techniques: photometric ; techniques: radial velocities
[en] We report on the discovery of a new extremely short period transiting extrasolar planet, WASP-19b. The planet has mass M [SUB]pl[/SUB] = 1.15 Â± 0.08 M[SUB]J[/SUB] , radius R [SUB]pl[/SUB] = 1.31 Â± 0.06 R[SUB]J[/SUB] , and orbital period P = 0.7888399 Â± 0.0000008 days. Through spectroscopic analysis, we determine the host star to be a slightly super-solar metallicity ([M/H] = 0.1 Â± 0.1 dex) G-dwarf with T [SUB]eff[/SUB] = 5500 Â± 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 [SUB]rot[/SUB] = 10.5 Â± 0.2 days. The relatively short stellar rotation period suggests that either WASP-19 is somewhat young (~ 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'[SUB] s [/SUB], if a more precise age is determined.