The low density transiting exoplanet WASP-15b

We report the discovery of a low-density exoplanet transiting an 11th magnitude star in the Southern hemisphere. WASP-15b, which orbits its host star with a period P = 3.7520656 +/- 0.0000028 d, has a mass M(p) = 0.542 +/- 0.050 M(J) and radius R(p) = 1.428 +/- 0.077 R(J), and is therefore one of the least dense transiting exoplanets so far discovered (rho(p) = 0.247 +/- 0.035 g cm(-3)). An analysis of the spectrum of the host star shows it to be of spectral type around F5, with an effective temperature T(eff) 6300 +/- 100 K and [Fe/H] = -0.17 +/- 0.11.