Physical properties of the HAT-P-23 and WASP-48 planetary systems from multi-colour photometry

Abstract

Accurate and repeated photometric follow-up observations of planetary-transit events are important to precisely characterize the physical properties of exoplanets. A good knowledge of the main characteristics of the exoplanets is fundamental to trace their origin and evolution. Multi-band photometric observations play an important role in this process. By using new photometric data, we computed precise estimates of the physical properties of two transiting planetary systems. We present new broad-band, multi-colour, photometric observations obtained using three small class telescopes and the telescope-defocussing technique. For each of the two targets, one transit event was simultaneously observed through four optical filters. One transit of WASP-48 b was monitored with two telescopes from the same observatory. The physical parameters of the systems were obtained by fitting the transit light curves with {\sc jktebop} and from published spectroscopic measurements. We have revised the physical parameters of the two planetary systems, finding a smaller radius for both HAT-P-23 b and WASP-48 b, $R_b=1.224\pm 0.037R_{Jup}$ and $R_b=1.396\pm 0.051R_{Jup}$, respectively, than those measured in the discovery papers ($R_b=1.368\pm 0.090R_{Jup}$ and $R_b=1.67\pm 0.10R_{Jup}$). The density of the two planets are higher than those previously published (${\rho }_b$ ~1.1 and ~0.3 ${\rho }_{jup}$ for HAT-P-23 and WASP-48 respectively) hence the two Hot Jupiters are no longer located in a parameter space region of highly inflated planets. An analysis of the variation of the planet's measured radius as a function of optical wavelength reveals flat transmission spectra within the experimental uncertainties. We also confirm the presence of the eclipsing contact binary NSVS-3071474 in the same field of view of WASP-48, for which we refine the value of the period to be 0.459 d.

11 pages, 12 figures, accepted for publication in A&A

References in corpus (17)

• The Dartmouth Stellar Evolution Database
• The effect of red noise on planetary transit detection
• Improved parameters for extrasolar transiting planets
• Homogeneous studies of transiting extrasolar planets. I. Light curve analyses
• Improving Stellar and Planetary Parameters of Transiting Planet Systems: The Case of TrES-2
• 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
• The Transit Light Curve Project. VII. The Not-So-Bloated Exoplanet HAT-P-1b
• High-precision photometry by telescope defocussing. VI. WASP-24, WASP-25 and WASP-26
• Hot-Jupiter Inflation due to Deep Energy Deposition
• A lower radius and mass for the transiting extrasolar planet HAT-P-8b
• Physical properties, starspot activity, orbital obliquity, and transmission spectrum of the Qatar-2 planetary system from multi-colour photometry
• Transit Timing Analysis in the HAT-P-32 system
• Physical properties of the WASP-67 planetary system from multi-colour photometry
• Physical properties of the WASP-44 planetary system from simultaneous multi-colour photometry
• The GAPS Programme with HARPS-N@TNG VI: The Curious Case of TrES-4b

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• ACCESS: An optical transmission spectrum of the high-gravity, hot Jupiter HAT-P-23b
• Planet-star interactions with precise transit timing. III. Entering the regime of dynamical tides
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