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 (?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.

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