Physical properties and transmission spectrum of the WASP-80 planetary system from multi-colour photometry^⋆

¹ Max Planck Institute for Astronomy, Königstuhl 17, 69117 Heidelberg, Germany
e-mail: mancini@mpia.de
² Astrophysics Group, Keele University, Keele, ST5 5BG, UK
³ SUPA, University of St Andrews, School of Physics & Astronomy, North Haugh, St Andrews KY16 9SS, UK
⁴ Niels Bohr Institute, University of Copenhagen, Juliane Maries vej 30, 2100 Copenhagen Ø, Denmark
⁵ Centre for Star and Planet Formation, Geological Museum, Øster Voldgade 5-7, 1350 Copenhagen, Denmark
⁶ INAF-Osservatorio Astrofisico di Catania, via S.Sofia 78, 95123 Catania, Italy
⁷ Instituto de Astrofísica, Facultad de Física, Pontificia Universidad Católica de Chile, Av. Vicuña Mackenna 4860, 7820436 Macul, Santiago, Chile
⁸ Max-Planck-Institute for Solar System Research, Max-Planck Str. 2, 37191 Katlenburg-Lindau, Germany
⁹ Qatar Foundation, PO Box 5825, Doha, Qatar
¹⁰ Dipartimento di Fisica “E.R. Caianiello”, University of Salerno, via Giovanni Paolo II, 84084 Fisciano, Italy
¹¹ Istituto Nazionale di Fisica Nucleare, Sezione di Napoli, Napoli, Italy
¹² Qatar Environment and Energy Research Institute, Qatar Foundation, Tornado Tower, Floor 19, PO Box 5825, Doha, Qatar
¹³ Istituto Internazionale per gli Alti Studi Scientifici (IIASS), 84019 Vietri Sul Mare, Italy
¹⁴ European Southern Observatory, Karl-Schwarzschild-Straße 2, 85748 Garching bei München, Germany
¹⁵ Yunnan Observatory, Chinese Academy of Sciences, 650011 Kunming, PR China
¹⁶ Key Laboratory for the Structure and Evolution of Celestial Objects, Chinese Academy of Sciences, 650011 Kunming, PR China
¹⁷ Korea Astronomy and Space Science Institute, 305-348 Daejeon, Republic of Korea
¹⁸ Finnish Centre for Astronomy with ESO (FINCA), University of Turku, Väisäläntie 20, 21500 Piikkiö, Finland
¹⁹ Department of Physics, Sharif University of Technology, PO Box 11155-9161 Tehran, Iran
²⁰ Perimeter Institute for Theoretical Physics, 31 Caroline St. N., Waterloo N2L 2Y5, Canada
²¹ Las Cumbres Observatory Global Telescope Network, 6740B Cortona Drive, Goleta CA 93117, USA
²² Institut d’Astrophysique et de Géophysique, Université de Liège, 4000 Liège, Belgium
²³ School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London E1 4NS, UK

Received: 17 December 2013
Accepted: 18 January 2014

Abstract

WASP-80 is one of only two systems known to contain a hot Jupiter which transits its M-dwarf host star. We present eight light curves of one transit event, obtained simultaneously using two defocussed telescopes. These data were taken through the Bessell I, Sloan g′r′i′z′ and near-infrared JHK passbands. We use our data to search for opacity-induced changes in the planetary radius, but find that all values agree with each other. Our data are therefore consistent with a flat transmission spectrum to within the observational uncertainties. We also measure an activity index of the host star of log R '_HK = -4.495, meaning that WASP-80 A shows strong chromospheric activity. The non-detection of starspots implies that, if they exist, they must be small and symmetrically distributed on the stellar surface. We model all available optical transit light curves and obtain improved physical properties and orbital ephemerides for the system.