University ’ S Repository of Research Publications and Other Research Outputs WASP-54 B , WASP-56 B , and WASP-57 B : Three New Sub-Jupiter Mass Planets from SuperWASP Journal Article

We present three newly discovered sub-Jupiter mass planets from the SuperWASP survey: WASP-54b is a heavily bloated pla net of mass 0.636 +0.025 −0.024 MJ and radius 1.653 +0.090 −0.083 RJ. It orbits a F9 star, evolving o ff the main sequence, every 3.69 days. Our MCMC fit of the system yields a slightly eccentric orbit ( e = 0.067+0.033 −0.025) for WASP-54b. We investigated further the veracity of our d etection of the eccentric orbit for WASP-54b, and we find that it could be real . However, given the brightness of WASP-54 V =10.42 magnitudes, we encourage observations of a secondary eclipse to draw robus t conclusions on both the orbital eccentricity and the therm al structure of the planet. WASP-56b and WASP-57b have masses of 0.571 +0.034 −0.035 MJ and 0.672 +0.049 −0.046 MJ , respectively; and radii of 1 .092 +0.035 −0.033 RJ for WASP-56b and 0 .916+0.017 −0.014 RJ for WASP-57b. They orbit main sequence stars of spectral typ e G6 every 4.67 and 2.84 days, respectively. WASP-56b and WASP-57b show no radius anomaly and a high density possibly implying a large core of heavy ele m nts; possibly as high as∼50 M⊕ in the case of WASP-57b. However, the composition of the deep interior of exoplanets remain still undetermined. Thus, more exoplanet discoveries such as the ones presented in this paper, are needed to understand and co nstrain giant planets’ physical properties.