stars: fundamental parameters; stars: individual: WASP-57; planetary systems
Abstract :
[en] Transits in the WASP-57 planetary system have been found to occur half an hour earlier than expected. We present 10 transit light curves from amateur telescopes, on which this discovery was based, 13 transit light curves from professional facilities which confirm and refine this finding, and high-resolution imaging which show no evidence for nearby companions. We use these data to determine a new and precise orbital ephemeris, and measure the physical properties of the system. Our revised orbital period is 4.5 s shorter than found from the discovery data alone, which explains the early occurrence of the transits. We also find both the star and planet to be larger and less massive than previously thought. The measured mass and radius of the planet are now consistent with theoretical models of gas giants containing no heavy-element core, as expected for the subsolar metallicity of the host star. Two transits were observed simultaneously in four passbands. We use the resulting light curves to measure the planet's radius as a function of wavelength, finding that our data are sufficient in principle but not in practise to constrain its atmospheric properties. We conclude with a discussion of the current and future status of transmission photometry studies for probing the atmospheres of gas-giant transiting planets.
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Southworth, John; Astrophysics Group, Keele University, Staffordshire ST5 5BG, UK
Mancini, L.; Max Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg, Germany
Tregloan-Reed, J.; NASA Ames Research Center, Moffett Field, CA 94035, USA
Calchi Novati, S.; NASA Exoplanet Science Institute, MS 100-22, California Institute of Technology, Pasadena, CA 91125, USA ; Dipartimento di Fisica `E.R. Caianiello', Università di Salerno, Via Giovanni Paolo II 132, I-84084 Fisciano (SA), Italy ; Istituto Internazionale per gli Alti Studi Scientifici (IIASS), I-84019 Vietri Sul Mare (SA), Italy
Ciceri, S.; Max Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg, Germany
D'Ago, G.; Istituto Internazionale per gli Alti Studi Scientifici (IIASS), I-84019 Vietri Sul Mare (SA), Italy ; Dipartimento di Fisica `E.R. Caianiello', Università di Salerno, Via Giovanni Paolo II 132, I-84084 Fisciano (SA), Italy ; Istituto Nazionale di Fisica Nucleare, Sezione di Napoli, I-80126 Napoli, Italy
Delrez, Laetitia ; Université de Liège > Département d'astrophys., géophysique et océanographie (AGO) > Origines Cosmologiques et Astrophysiques (OrCa)
Dominik, M.; SUPA, University of St Andrews, School of Physics & Astronomy, North Haugh, St Andrews KY16 9SS, UK
Evans, D. F.; Astrophysics Group, Keele University, Staffordshire ST5 5BG, UK
Jehin, Emmanuel ; Université de Liège > Département d'astrophys., géophysique et océanographie (AGO) > Origines Cosmologiques et Astrophysiques (OrCa)
Jørgensen, U. G.; Niels Bohr Institute & Centre for Star and Planet Formation, University of Copenhagen, Øster Voldgade 5, DK-1350 Copenhagen, Denmark
Haugbølle, T.; Niels Bohr Institute & Centre for Star and Planet Formation, University of Copenhagen, Øster Voldgade 5, DK-1350 Copenhagen, Denmark
Lendl, M.; Institut d'Astrophysique et de Géophysique, Université de Liège, B-4000 Liège, Belgium ; Observatoire de Genève, Université de Genève, Chemin des maillettes 51, CH-1290 Sauverny, Switzerland
Arena, C.; Sezione Pianeti Extrasolari - Unione Astrofili Italiani (UAI) ; Gruppo Astrofili Catanesi - Catania, Italy
Barbieri, M.; Department of Physics, University of Atacama, Copayapu 485, Copiapo, Chile
Corfini, G.; Sezione Pianeti Extrasolari - Unione Astrofili Italiani (UAI)
Lopresti, C.; Sezione Pianeti Extrasolari - Unione Astrofili Italiani (UAI) ; Istituto Spezzino Ricerche Astronomiche - I.R.A.S., La Spezia, Italy
Marchini, A.; Sezione Pianeti Extrasolari - Unione Astrofili Italiani (UAI) ; DSFTA - Astronomical Observatory, University of Siena, Via Roma 56, I-53100 Siena, Italy
Marino, G.; Sezione Pianeti Extrasolari - Unione Astrofili Italiani (UAI) ; Gruppo Astrofili Catanesi (GAC) - Catania, Italy
Alsubai, K. A.; Qatar Environment and Energy Research Institute, Qatar Foundation, Tornado Tower, Floor 19, 5825 Doha, Qatar
Bozza, V.; Dipartimento di Fisica `E.R. Caianiello', Università di Salerno, Via Giovanni Paolo II 132, I-84084 Fisciano (SA), Italy ; Istituto Nazionale di Fisica Nucleare, Sezione di Napoli, I-80126 Napoli, Italy
Bramich, D. M.; Qatar Environment and Energy Research Institute, Qatar Foundation, Tornado Tower, Floor 19, 5825 Doha, Qatar
Jaimes, R. Figuera; SUPA, University of St Andrews, School of Physics & Astronomy, North Haugh, St Andrews KY16 9SS, UK ; European Southern Observatory, Karl-Schwarzschild-Straße 2, D-85748 Garching bei München, Germany
Hinse, T. C.; Korea Astronomy and Space Science Institute, Daejeon 305-348, Republic of Korea
Henning, Th; Max Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg, Germany
Hundertmark, M.; Niels Bohr Institute & Centre for Star and Planet Formation, University of Copenhagen, Øster Voldgade 5, DK-1350 Copenhagen, Denmark
Juncher, D.; Niels Bohr Institute & Centre for Star and Planet Formation, University of Copenhagen, Øster Voldgade 5, DK-1350 Copenhagen, Denmark
Korhonen, H.; Niels Bohr Institute & Centre for Star and Planet Formation, University of Copenhagen, Øster Voldgade 5, DK-1350 Copenhagen, Denmark ; Finnish Centre for Astronomy with ESO (FINCA), University of Turku, Väisäläntie 20, FI-21500 Piikkiö, Finland
Popovas, A.; Niels Bohr Institute & Centre for Star and Planet Formation, University of Copenhagen, Øster Voldgade 5, DK-1350 Copenhagen, Denmark
Rabus, M.; Max Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg, Germany ; Instituto de Astrofısica, Facultad de Fısica, Pontificia Universidad Católica de Chile, Av. Vicuña Mackenna 4860, 7820436 Macul, Santiago, Chile
Rahvar, S.; Department of Physics, Sharif University of Technology, 11155-9161 Tehran, Iran
Schmidt, R. W.; Astronomisches Rechen-Institut, Zentrum für Astronomie, Universität Heidelberg, Mönchhofstraße 12-14, D-69120 Heidelberg, Germany
Skottfelt, J.; Niels Bohr Institute & Centre for Star and Planet Formation, University of Copenhagen, Øster Voldgade 5, DK-1350 Copenhagen, Denmark ; Centre of Electronic Imaging, Department of Physical Sciences, The Open University, Milton Keynes MK7 6AA, UK
Snodgrass, C.; Planetary and Space Sciences, Department of Physical Sciences, The Open University, Milton Keynes MK7 6AA, UK
Starkey, D.; SUPA, University of St Andrews, School of Physics & Astronomy, North Haugh, St Andrews KY16 9SS, UK
Surdej, Jean ; Université de Liège > Département d'astrophys., géophysique et océanographie (AGO) > Astroph. extragalactique et observations spatiales (AEOS)
Wertz, Olivier ; Université de Liège > Département d'astrophys., géophysique et océanographie (AGO) > Astroph. extragalactique et observations spatiales (AEOS)
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