High-precision photometry by telescope defocussing. II. The transiting planetary system WASP-4

Abstract

We present and analyse light curves of four transits of the Southern hemisphere extrasolar planetary system WASP-4, obtained with a telescope defocussed so the radius of each point spread function was 17 arcsec (44 pixels). This approach minimises both random and systematic errors, allowing us to achieve scatters of between 0.60 and 0.88 mmag per observation over complete transit events. The light curves are augmented by published observations and analysed using the JKTEBOP code. The results of this process are combined with theoretical stellar model predictions to derive the physical properties of the WASP-4 system. We find that the mass and radius of the planet are M_b = 1.289 {+0.090 -0.090} {+0.039 -0.000} MJup and R_b = 1.371 {+0.032 -0.035} {+0.021 -0.000} RJup, respectively (statistical and systematic uncertainties). These quantities give a surface gravity and density of g_b = 17.03 +0.97 -0.54 m/s2 and rho_b = 0.500 {+0.032 -0.021} {+0.000 -0.008} rhoJup, and fit the trends for short-period extrasolar planets to have relatively high masses and surface gravities. WASP-4 is now one of the best-quantified transiting extrasolar planetary systems, and significant further progress requires improvements to our understanding of the physical properties of low-mass stars.

Accepted for publication in MNRAS. 8 pages plus appendix, 4 figures, 8 tables

References in corpus (19)

• Improved parameters for extrasolar transiting planets
• Homogeneous studies of transiting extrasolar planets. I. Light curve analyses
• Efficient identification of exoplanetary transit candidates from SuperWASP light curves
• The Transit Light Curve Project. IX. Evidence for a Smaller Radius of the Exoplanet XO-3b
• WASP-1b and WASP-2b: Two new transiting exoplanets detected with SuperWASP and SOPHIE
• Hubble Space Telescope times-series photometry of the planetary transit of HD189733: no moon, no rings, starspots
• High-precision photometry by telescope defocussing. I. The transiting planetary system WASP-5
• Improved parameters for the transiting hot Jupiters WASP-4b and WASP-5b
• WASP-4b: a 12th-magnitude transiting hot-Jupiter in the Southern hemisphere
• Homogeneous studies of transiting extrasolar planets. II. Physical properties
• A method for the direct determination of the surface gravities of transiting extrasolar planets
• High accuracy transit photometry of the planet OGLE-TR-113b with a new deconvolution-based method
• A Smaller Radius for the Transiting Exoplanet WASP-10b
• The Transit Light Curve Project. VII. The Not-So-Bloated Exoplanet HAT-P-1b
• The Transit Light Curve Project. XI. Submillimagnitude Photometry of Two Transits of the Bloated Planet WASP-4b
• The AGN and Gas Disk in the Low Surface Brightness Galaxy PGC045080
• Limits to the planet candidate GJ 436c
• H-band thermal emission from the 19-hour period planet WASP-19b
• Eclipsing binaries observed with the WIRE satellite I. Discovery and photometric analysis of the new bright A0IV eclipsing binary Psi Centauri

Cited by in corpus (61)

• Homogeneous studies of transiting extrasolar planets. IV. Thirty systems with space-based light curves
• Homogeneous studies of transiting extrasolar planets. III. Additional planets and stellar models
• WASP-17b: an ultra-low density planet in a probable retrograde orbit
• Starspots and spin-orbit alignment in the WASP-4 exoplanetary system
• Homogeneous studies of transiting extrasolar planets. V. New results for 38 planets
• Transits and starspots in the WASP-19 planetary system
• Constraining Tidal Dissipation in Stars from The Destruction Rates of Exoplanets
• Physical properties of the 0.94-day period transiting planetary system WASP-18
• Extrasolar Planet Transits Observed at Kitt Peak National Observatory
• Physical properties, transmission and emission spectra of the WASP-19 planetary system from multi-colour photometry
• Transit timing variation in exoplanet WASP-3b
• MuSCAT: a multicolor simultaneous camera for studying atmospheres of transiting exoplanets
• Benchmarking the power of amateur observatories for TTV exoplanets detection
• ExoClock Project III: 450 new exoplanet ephemerides from ground and space observations
• Secondary Eclipse Photometry of WASP-4b with Warm Spitzer
• A simple model of the reflection effect for the interacting binaries and extrasolar planets
• Tidal Heating Models for the Radii of the Inflated Transiting Giant Planets WASP-4b, WASP-6b, WASP-12b, and TrES-4
• Transits and starspots in the WASP-6 planetary system
• TERMS Photometry of Known Transiting Exoplanets
• The GAPS Programme with HARPS-N at TNG. III: The retrograde orbit of HAT-P-18b
• High-precision photometry by telescope defocussing. IV. Confirmation of the huge radius of WASP-17b
• Physical properties and radius variations in the HAT-P-5 planetary system from simultaneous four-colour photometry
• High-precision photometry by telescope defocussing. III. The transiting planetary system WASP-2
• DONUTS: A science frame autoguiding algorithm with sub-pixel precision, capable of guiding on defocused stars
• ExoClock project II: A large-scale integrated study with 180 updated exoplanet ephemerides
• High-precision photometry of WASP-12 b transits
• Refined physical properties of the HAT-P-13 planetary system
• Explorations into the Viability of Coupled Radius-Orbit Evolutionary Models for Inflated Planets
• Homogeneously derived transit timings for 17 exoplanets and reassessed TTV trends for WASP-12 and WASP-4
• TASTE: The Asiago Search for Transit timing variations of Exoplanets. I. Overview and improved parameters for HAT-P-3b and HAT-P-14b
• Gemini/GMOS Transmission Spectral Survey: Complete Optical Transmission Spectrum of the hot Jupiter WASP-4b
• Transit Observations of the WASP-10 System
• Characterizing Transiting Extrasolar Planets with Narrow-Band Photometry and GTC/OSIRIS
• Simultaneous follow-up of planetary transits: revised physical properties for the planetary systems HAT-P-16 and WASP-21
• Transit timing variations in the WASP-4 planetary system
• No Transit Timing Variations in WASP-4
• Multi-filter transit observations of WASP-39b and WASP-43b with three San Pedro Mártir telescopes
• An extremely high photometric precision in ground-based observations of two transits in the WASP-50 planetary system
• Secondary Eclipse Photometry of the Exoplanet WASP-5b with Warm Spitzer
• TraMoS project III: Improved physical parameters, timing analysis, and star-spot modelling of the WASP-4b exoplanet system from 38 transit observations
• Broad-band spectrophotometry of HAT-P-32 b: Search for a scattering signature in the planetary spectrum
• TASTE. III. A homogeneous study of transit time variations in WASP-3b
• WASP-4b Transit Observations With GROND
• A ground-based Ks-band detection of the thermal emission from the transiting exoplanet WASP-4b
• Examining the orbital decay targets KELT-9 b, KELT-16 b and WASP-4 b, and the transit-timing variations of HD 97658 b
• Absolute dimensions of detached eclipsing binaries. III. The metallic-lined system YZ Cassiopeiae
• MCMCI: A code to fully characterise an exoplanetary system
• Ground-based transit observations of the HAT-P-18, HAT-P-19, HAT-P-27/WASP-40 and WASP-21 systems
• Possible detection of a bimodal cloud distribution in the atmosphere of HAT-P-32\,A\,b from multi-band photometry
• WASP-4 transit timing variation from a comprehensive set of 129 transits
• Probing Transit Timing Variation and its Possible Origin with Twelve New Transits of TrES-3b
• The Invisible Majority? Evolution and Detection of Outer Planetary Systems without Gas Giants
• Orbital periods of cataclysmic variables identified by the SDSS. VII. Four new eclipsing systems
• Finding Mountains with Molehills: The Detectability of Exotopography
• A possible misaligned orbit for the young planet AU Mic c
• Photometric Follow-up Transit (Primary Eclipse) Observations of WASP-43 b and TrES-3b and A Study on Their Transit Timing Variations
• Warm Spitzer Occultation Photometry of WASP-26b at 3.6μm and 4.5μm
• A search for transit timing variations in the HATS-18 planetary system
• HSTEP -- Homogeneous Studies of Transiting Extrasolar Planets
• A search for transit timing variations in the transiting hot Jupiter systems HIP 65, NGTS-6, NGTS-10 and WASP-173
• 5 Years of Defocused Observations of Exoplanet Transits with T100: Timing Perspective