WASP-54b, WASP-56b and WASP-57b: Three new sub-Jupiter mass planets from SuperWASP

Abstract

We present three newly discovered sub-Jupiter mass planets from the SuperWASP survey: WASP-54b is a heavily bloated planet of mass 0.636${}_{-0.024}^{+0.025}$ \mj and radius 1.653${}_{-0.083}^{+0.090}$ \rj. It orbits a F9 star, evolving off the main sequence, every 3.69 days. Our MCMC fit of the system yields a slightly eccentric orbit ($e=0.067_{-0.025}^{+0.033}$) for WASP-54b. We investigated further the veracity of our detection 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 robust conclusions on both the orbital eccentricity and the thermal structure of the planet. WASP-56b and WASP-57b have masses of 0.571${}_{-0.035}^{+0.034}$ \mj and $0.672_{-0.046}^{+0.049}$ \mj, respectively; and radii of $1.092_{-0.033}^{+0.035}$ \rj for WASP-56b and $0.916_{-0.014}^{+0.017}$ \rj for WASP-57b. They orbit main sequence stars of spectral type 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 elements; possibly as high as $\sim$50 M${}_{\oplus }$ 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 constrain giant planets' physical properties.

15pages, 19 figures, Submitted to A&A 8-10-2012 Accepted for publication 23-12-2012

References in corpus (15)

• Obliquities of Hot Jupiter host stars: Evidence for tidal interactions and primordial misalignments
• Formation of Hot Planets by a combination of planet scattering, tidal circularization, and Kozai mechanism
• Efficient identification of exoplanetary transit candidates from SuperWASP light curves
• The ACS Nearby Galaxy Survey Treasury IX. Constraining asymptotic giant branch evolution with old metal-poor galaxies
• WASP-3b: a strongly-irradiated transiting gas-giant planet
• A fast hybrid algorithm for exoplanetary transit searches
• Misaligned spin-orbit in the XO-3 planetary system?
• Heat transport in giant (exo)planets: a new perspective
• Three-Dimensional Atmospheric Circulation Models of HD 189733b and HD 209458b with Consistent Magnetic Drag and Ohmic Dissipation
• Improved parameters for the transiting hot Jupiters WASP-4b and WASP-5b
• HAT-P-12b: A Low-Density Sub-Saturn Mass Planet Transiting a Metal-Poor K Dwarf
• Measurement of the Spin-Orbit Alignment in the Exoplanetary System HD 189733
• WASP-42 b and WASP-49 b: two new transiting sub-Jupiters
• The shocking transit of WASP-12b: Modelling the observed early ingress in the near ultraviolet
• Ohmic Dissipation in the Interiors of Hot Jupiters

Cited by in corpus (20)

• Probabilistic Forecasting of the Masses and Radii of Other Worlds
• The GAPS Programme with HARPS-N@TNG XIV. Investigating giant planet migration history via improved eccentricity and mass determination for 231 transiting planets
• Determining stellar macroturbulence using asteroseismic rotational velocities from Kepler
• Evidence of an Upper Bound on the Masses of Planets and its Implications for Giant Planet Formation
• A library of ATMO forward model transmission spectra for hot Jupiter exoplanets
• New and updated stellar parameters for 90 transit hosts. The effect of the surface gravity
• TESS Transit Timing of Hundreds of Hot Jupiters
• From dense hot Jupiter to low-density Neptune: The discovery of WASP-127b, WASP-136b and WASP-138b
• ExoClock Project III: 450 new exoplanet ephemerides from ground and space observations
• HAT-P-65b and HAT-P-66b: Two Transiting Inflated Hot Jupiters and Observational Evidence for the Re-Inflation of Close-In Giant Planets
• Discrepancies between isochrone fitting and gyrochronology for exoplanet host stars?
• ExoClock project II: A large-scale integrated study with 180 updated exoplanet ephemerides
• A multiplicity study of transiting exoplanet host stars. I. High-contrast imaging with VLT/SPHERE
• ExoClock Project: An open platform for monitoring the ephemerides of Ariel targets with contributions from the public
• On a Possible Solution to the Tidal Realignment Problem for Hot Jupiters
• The homogeneous characterisation of Ariel host stars
• Larger and faster: revised properties and a shorter orbital period for the WASP-57 planetary system from a pro-am collaboration
• Precise Transit Photometry Using TESS II: Revisiting 28 Additional Transiting Systems With Updated Physical Properties
• Two transiting hot Jupiters from the WASP survey: WASP-150b and WASP-176b
• Original Research By Young Twinkle Students (ORBYTS): Ephemeris Refinement of Transiting Exoplanets III