Physical properties, transmission and emission spectra of the WASP-19 planetary system from multi-colour photometry
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We present new ground-based, multi-colour, broad-band photometric measurements of the physical parameters, transmission and emission spectra of the transiting extrasolar planet WASP-19b. The measurements are based on observations of eight transits and four occultations through a Gunn i filter using the 1.54-m Danish Telescope, 14 transits through an Rc filter at the Perth Exoplanet Survey Telescope (PEST) observatory and one transit observed simultaneously through four optical (Sloan g′, r′, i′, z′) and three near-infrared (J, H, K) filters, using the Gamma Ray Burst Optical and Near-Infrared Detector (GROND) instrument on the MPG/ESO 2.2-m telescope. The GROND optical light curves have a point-to-point scatter around the best-fitting model between 0.52 and 0.65 mmag rms. We use these new data to measure refined physical parameters for the system. We find the planet to be more bloated (Rb = 1.410 ± 0.017RJup; Mb = 1.139 ± 0.030MJup) and the system to be twice as old as initially thought. We also used published and archived data sets to study the transit timings, which do not depart from a linear ephemeris. We detected an anomaly in the GROND transit light curve which is compatible with a spot on the photosphere of the parent star. The starspot position, size, spot contrast and temperature were established. Using our new and published measurements, we assembled the planet's transmission spectrum over the 370–2350 nm wavelength range and its emission spectrum over the 750–8000 nm range. By comparing these data to theoretical models we investigated the theoretically predicted variation of the apparent radius of WASP-19b as a function of wavelength and studied the composition and thermal structure of its atmosphere. We conclude that: (i) there is no evidence for strong optical absorbers at low pressure, supporting the common idea that the planet's atmosphere lacks a dayside inversion; (ii) the temperature of the planet is not homogenized, because the high warming of its dayside causes the planet to be more efficient in re-radiating than redistributing energy to the night side; (iii) the planet seems to be outside of any current classification scheme.
Mancini , L , Ciceri , S , Chen , G , Tregloan-Reed , J , Fortney , J J , Southworth , J , Tan , T G , Burgdorf , M , Calchi Novati , S , Dominik , M , Fang , X-S , Finet , F , Gerner , T , Hardis , S , Hinse , T C , Jørgensen , U G , Liebig , C E , Nikolov , N , Ricci , D , Schäfer , S , Schönebeck , F , Skottfelt , J , Wertz , O , Alsubai , K A , Bozza , V , Browne , P , Dodds , P , Gu , S-H , Harpsøe , K , Henning , T , Hundertmark , M P G , Jessen-Hansen , J , Kains , N , Kerins , E , Kjeldsen , H , Lund , M N , Lundkvist , M , Madhusudhan , N , Mathiasen , M , Penny , M T , Proft , S , Rahvar , S , Sahu , K , Scarpetta , G , Snodgrass , C & Surdej , J 2013 , ' Physical properties, transmission and emission spectra of the WASP-19 planetary system from multi-colour photometry ' Monthly Notices of the Royal Astronomical Society , vol. 436 , no. 1 , pp. 2-18 . DOI: 10.1093/mnras/stt1394
Monthly Notices of the Royal Astronomical Society
© 2013 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society
DescriptionOperation of the Danish telescope is based on a grant to UGJ by the Danish Natural Science Research Council (FNU). JS acknowledges financial support from STFC in the form of an Advanced Fellowship. The research leading to these results has received funding from the European Community's Seventh Framework Programme (FP7/2007-2013/) under grant agreement Nos. 229517 and 268421. Funding for the Centre for Star and Planet Formation (StarPlan) and the Stellar Astrophysics Centre (SAC) is provided by The Danish National Research Foundation. MD, MH, CL and CS acknowledge the Qatar Foundation for support from QNRF grant NPRP-09-476-1-078. SG and XF acknowledge the support from NSFC under the grant No. 10873031. SG acknowledges the support from Chinese Academy of Sciences (grant No. KJCX2-YW-T24). The research is supported by the ASTERISK project (ASTERoseismic Investigations with SONG and Kepler) funded by the European Research Council (grant agreement No. 267864). OW (FNRS research fellow), FF (ARC PhD student), DR (FRIA PhD student) and JS acknowledge support from the Communauté française de Belgique – Actions de recherche concertées – Académie Wallonie-Europe. TCH acknowledges financial support from the Korea Research Council for Fundamental Science and Technology (KRCF) through the Young Research Scientist Fellowship Program and is supported by the KASI (Korea Astronomy and Space Science Institute) grant 2012-1-410-02/2013-9-400-00.
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