stars: fundamental parameters; stars: individual: WASP-17; planetary systems
Abstract :
[en] We present photometric observations of four transits in the WASP-17 planetary system, obtained using telescope defocusing techniques and with scatters reaching 0.5 mmag per point. Our revised orbital period is 4.0 ± 0.6 s longer than previous measurements, a difference of 6.6σ, and does not support the published detections of orbital eccentricity in this system. We model the light curves using the JKTEBOP code and calculate the physical properties of the system by recourse to five sets of theoretical stellar model predictions. The resulting planetary radius, R[SUB]b[/SUB] = 1.932 ± 0.052 ± 0.010 R[SUB]Jup[/SUB] (statistical and systematic errors, respectively), provides confirmation that WASP-17 b is the largest planet currently known. All 14 planets with radii measured to be greater than 1.6 R[SUB]Jup[/SUB] are found around comparatively hot (T[SUB]eff[/SUB] > 5900 K) and massive (M[SUB]A[/SUB] > 1.15 M[SUB]&sun;[/SUB]) stars. Chromospheric activity indicators are available for eight of these stars, and all imply a low activity level. The planets have small or zero orbital eccentricities, so tidal effects struggle to explain their large radii. The observed dearth of large planets around small stars may be natural but could also be due to observational biases against deep transits, if these are mistakenly labelled as false positives and so not followed up. Based on data collected by MiNDSTEp with the Danish 1.54-m telescope at the ESO La Silla Observatory.Royal Society University Research Fellow.
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Southworth, John; Astrophysics Group, Keele University, Staffordshire, ST5 5BG
Hinse, T. C.; Korea Astronomy and Space Science Institute, Daejeon, 305-348 Republic of Korea
Dominik, M.; SUPA, University of St Andrews, School of Physics & Astronomy, North Haugh St Andrews, KY16 9SS
Fang, X.-S.; National Astronomical Observatories/Yunnan Observatory, Chinese Academy of Sciences, Kunming, 650011 China
Harpsøe, K.; Niels Bohr Institute, University of Copenhagen, Juliane Maries vej 30 2100 Copenhagen Ø, Denmark ; Centre for Star and Planet Formation, Natural History Museum of Denmark, University of Copenhagen, øster Voldgade 5-7 1350 Copenhagen K, Denmark
Jørgensen, U. G.; Niels Bohr Institute, University of Copenhagen, Juliane Maries vej 30 2100 Copenhagen Ø, Denmark ; Centre for Star and Planet Formation, Natural History Museum of Denmark, University of Copenhagen, øster Voldgade 5-7 1350 Copenhagen K, Denmark
Kerins, E.; Jodrell Bank Centre for Astrophysics, University of Manchester, Oxford Road Manchester, M13 9PL
Liebig, C.; SUPA, University of St Andrews, School of Physics & Astronomy, North Haugh St Andrews, KY16 9SS
Mancini, L.; Max Planck Institute for Astronomy, Königstuhl 17 69117 Heidelberg, Germany ; Istituto Internazionale per gli Alti Studi Scientifici (IIASS), 84019 Vietri Sul Mare (SA), Italy
Skottfelt, J.; Niels Bohr Institute, University of Copenhagen, Juliane Maries vej 30 2100 Copenhagen Ø, Denmark ; Centre for Star and Planet Formation, Natural History Museum of Denmark, University of Copenhagen, øster Voldgade 5-7 1350 Copenhagen K, Denmark
Anderson, D. R.; Astrophysics Group, Keele University, Staffordshire, ST5 5BG
Smalley, B.; Astrophysics Group, Keele University, Staffordshire, ST5 5BG
Tregloan-Reed, J.; Astrophysics Group, Keele University, Staffordshire, ST5 5BG
Wertz, Olivier ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Astroph. extragalactique et observations spatiales (AEOS)
Alsubai, K. A.; Qatar Foundation, PO Box 5825 Doha, Qatar
Bozza, V.; Istituto Internazionale per gli Alti Studi Scientifici (IIASS), 84019 Vietri Sul Mare (SA), Italy ; Dipartimento di Fisica 'E. R. Caianiello', Università di Salerno, Via Ponte Don Melillo 84084 Fisciano (SA), Italy ; Istituto Nazionale di Fisica Nucleare, Sezione di Napoli Napoli, Italy
Calchi Novati, S.; Istituto Internazionale per gli Alti Studi Scientifici (IIASS), 84019 Vietri Sul Mare (SA), Italy ; Dipartimento di Fisica 'E. R. Caianiello', Università di Salerno, Via Ponte Don Melillo 84084 Fisciano (SA), Italy
Gu, S.-H.; National Astronomical Observatories/Yunnan Observatory, Chinese Academy of Sciences, Kunming, 650011 China
Hundertmark, M.; SUPA, University of St Andrews, School of Physics & Astronomy, North Haugh St Andrews, KY16 9SS ; Institut für Astrophysik, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1 37077 Göttingen, Germany
Jessen-Hansen, J.; Stellar Astrophysics Centre (SAC), Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120 DK-8000 Aarhus C, Denmark ; Nordic Optical Telescope, Apartado 474 E-38700 Santa Cruz de La Palma, Spain
Kains, N.; European Southern Observatory, Karl-Schwarzschild-Straße 2 85748 Garching bei München, Germany
Kjeldsen, H.; Stellar Astrophysics Centre (SAC), Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120 DK-8000 Aarhus C, Denmark
Lund, M. N.; Stellar Astrophysics Centre (SAC), Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120 DK-8000 Aarhus C, Denmark
Lundkvist, M.; Stellar Astrophysics Centre (SAC), Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120 DK-8000 Aarhus C, Denmark
Mathiasen, M.; Niels Bohr Institute, University of Copenhagen, Juliane Maries vej 30 2100 Copenhagen Ø, Denmark
Penny, M. T.; Jodrell Bank Centre for Astrophysics, University of Manchester, Oxford Road Manchester, M13 9PL ; Department of Astronomy, Ohio State University, 140 W. 18th Ave. Columbus, OH 43210 USA
Rahvar, S.; Department of Physics, Sharif University of Technology, PO Box 11155-9161 Tehran, Iran ; Perimeter Institute for Theoretical Physics, 31 Caroline Street North Waterloo, Ontario N2L 2Y5 Canada
Ricci, Davide ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Astroph. extragalactique et observations spatiales (AEOS)
Scarpetta, G.; Istituto Internazionale per gli Alti Studi Scientifici (IIASS), 84019 Vietri Sul Mare (SA), Italy ; Dipartimento di Fisica 'E. R. Caianiello', Università di Salerno, Via Ponte Don Melillo 84084 Fisciano (SA), Italy ; Istituto Nazionale di Fisica Nucleare, Sezione di Napoli Napoli, Italy
Snodgrass, C.; Max Planck Institute for Solar System Research, Max-Planck Str. 2 37191 Katlenburg-Lindau, Germany
Surdej, Jean ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Astroph. extragalactique et observations spatiales (AEOS)
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