CHEOPS finds KELT-1b darker than expected in visible light

Astronomy and Astrophysics, vol. 668, pp. A93

Abstract

Recent studies based on photometry from the Transiting Exoplanet Survey Satellite (TESS) have suggested that the dayside of KELT-1b, a strongly irradiated brown dwarf, is significantly brighter in visible light than what would be expected based on Spitzer observations in the infrared. We observed eight eclipses of KELT-1b with CHaracterising ExOPlanet Satellite (CHEOPS) to measure its dayside brightness temperature in the bluest passband observed so far, and we jointly modelled the CHEOPS photometry with the existing optical and near-infrared photometry from TESS, LBT, CFHT, and Spitzer. Our modelling has led to a self-consistent dayside spectrum for KELT-1b covering the CHEOPS, TESS, H, Ks, and Spitzer IRAC 3.6 and 4.5 µm bands, where our TESS, H, Ks, and Spitzer band estimates largely agree with the previous studies. However, we discovered a strong discrepancy between the CHEOPS and TESS bands. The CHEOPS observations yield a higher photometric precision than the TESS observations, but they do not show a significant eclipse signal, while a deep eclipse is detected in the TESS band. The derived TESS geometric albedo of 0.36−0.13+0.12 is difficult to reconcile with a CHEOPS geometric albedo that is consistent with zero because the two passbands have considerable overlap. Variability in cloud cover caused by the transport of transient nightside clouds to the dayside could provide an explanation for reconciling the TESS and CHEOPS geometric albedos, but this hypothesis needs to be tested by future observations.

Authors 81

1. H. Parviainen

   Universidad de La Laguna · Instituto de Astrofísica de Canarias

   Affiliation as printed

   Departamento de Astrofísica, Universidad de La Laguna (ULL), 38206 La Laguna, Tenerife, Spain

   Instituto de Astrofísica de Canarias (IAC), 38200 La Laguna, Tenerife, Spain

2. Thomas G Wilson

   University of St Andrews

   Affiliation as printed

   Centre for Exoplanet Science, SUPA School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews KY16 9SS, UK

3. M. Lendl

   University of Geneva

   Affiliation as printed

   Observatoire Astronomique de l’Université de Genève, Chemin Pegasi 51, 1290 Versoix, Switzerland

   Observatoire Astronomique de l'Université de Genève, Chemin Pegasi 51, 1290 Versoix, Switzerland

4. Daniel Kitzmann

   University of Bern · Center for Space and Habitability

   Affiliation as printed

   Center for Space and Habitability, University of Bern, Gesellschaftsstrasse 6, 3012 Bern, Switzerland

5. Ε. Πάλλη

   Universidad de La Laguna · Instituto de Astrofísica de Canarias

   Affiliation as printed

   Departamento de Astrofísica, Universidad de La Laguna (ULL), 38206 La Laguna, Tenerife, Spain

   Instituto de Astrofísica de Canarias (IAC), 38200 La Laguna, Tenerife, Spain

6. Luisa Maria Serrano

   University of Turin

   Affiliation as printed

   Dipartimento di Fisica, Università degli Studi di Torino, via Pietro Giuria 1, 10125, Torino, Italy

7. Erik A. Meier Valdés

   University of Bern · Center for Space and Habitability

   Affiliation as printed

   Center for Space and Habitability, University of Bern, Gesellschaftsstrasse 6, 3012 Bern, Switzerland

8. W. Benz

   University of Bern · Center for Space and Habitability

   Affiliation as printed

   Center for Space and Habitability, University of Bern, Gesellschaftsstrasse 6, 3012 Bern, Switzerland

   Physikalisches Institut, University of Bern, Sidlerstrasse 5, 3012 Bern, Switzerland

9. A. Deline

   University of Geneva

   Affiliation as printed

   Observatoire Astronomique de l’Université de Genève, Chemin Pegasi 51, 1290 Versoix, Switzerland

   Observatoire Astronomique de l'Université de Genève, Chemin Pegasi 51, 1290 Versoix, Switzerland

10. David Ehrenreich

    University of Geneva

    Affiliation as printed

    Observatoire Astronomique de l’Université de Genève, Chemin Pegasi 51, 1290 Versoix, Switzerland

    Observatoire Astronomique de l'Université de Genève, Chemin Pegasi 51, 1290 Versoix, Switzerland

11. P. Guterman

    Centre National de la Recherche Scientifique · Aix-Marseille Université · Division Technique de I'INSU · Institut National des Sciences de l'Univers

    Affiliation as printed

    Aix-Marseille Univ., CNRS, CNES, LAM, 38 rue Frédéric Joliot-Curie, 13388 Marseille, France

    Division Technique INSU, CS20330, 83507 La Seyne-sur-Mer Cedex, France

12. Kevin Heng

    University of Bern · University of Warwick · Center for Space and Habitability

    Affiliation as printed

    Center for Space and Habitability, University of Bern, Gesellschaftsstrasse 6, 3012 Bern, Switzerland

    Department of Physics, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK

13. Olivier D S Demangeon

    Universidade do Porto · Institute of Astrophysics and Space Sciences · Centro de Astrofísica da Universidade do Porto

    Affiliation as printed

    Departamento de Fisica e Astronomia, Faculdade de Ciencias, Universidade do Porto, Rua do Campo Alegre, 4169-007 Porto, Portugal

    Instituto de Astrofísica e Ciencias do Espaco, Universidade do Porto, CAUP, Rua das Estrelas, 4150-762 Porto, Portugal

14. A. Bonfanti

    Austrian Academy of Sciences · Space Research Institute

    Affiliation as printed

    Space Research Institute, Austrian Academy of Sciences, Schmiedlstrasse 6, 8042 Graz, Austria

15. Sébastien Salmon

    University of Geneva

    Affiliation as printed

    Observatoire Astronomique de l’Université de Genève, Chemin Pegasi 51, 1290 Versoix, Switzerland

    Observatoire Astronomique de l'Université de Genève, Chemin Pegasi 51, 1290 Versoix, Switzerland

16. V. Singh

    Osservatorio Astrofisico di Catania

    Affiliation as printed

    INAF, Osservatorio Astrofísico di Catania, Via S. Sofia 78, 95123 Catania, Italy

17. Nuno C. Santos

    Universidade do Porto · Institute of Astrophysics and Space Sciences · Centro de Astrofísica da Universidade do Porto

    Affiliation as printed

    Departamento de Fisica e Astronomia, Faculdade de Ciencias, Universidade do Porto, Rua do Campo Alegre, 4169-007 Porto, Portugal

    Instituto de Astrofísica e Ciencias do Espaco, Universidade do Porto, CAUP, Rua das Estrelas, 4150-762 Porto, Portugal

18. S. G. Sousa

    Universidade do Porto · Institute of Astrophysics and Space Sciences · Centro de Astrofísica da Universidade do Porto

    Affiliation as printed

    Instituto de Astrofísica e Ciencias do Espaco, Universidade do Porto, CAUP, Rua das Estrelas, 4150-762 Porto, Portugal

19. Yann Alibert

    University of Bern

    Affiliation as printed

    Physikalisches Institut, University of Bern, Sidlerstrasse 5, 3012 Bern, Switzerland

20. R. Alonso

    Universidad de La Laguna · Instituto de Astrofísica de Canarias

    Affiliation as printed

    Departamento de Astrofísica, Universidad de La Laguna (ULL), 38206 La Laguna, Tenerife, Spain

    Instituto de Astrofísica de Canarias (IAC), 38200 La Laguna, Tenerife, Spain

21. Guillem Anglada-Escudé

    Institute of Space Sciences · Institut d'Estudis Espacials de Catalunya

    Affiliation as printed

    Institut de Ciencies de l’Espai (ICE, CSIC), Campus UAB, Can Magrans s/n, 08193 Bellaterra, Spain

    Institut d’Estudis Espacials de Catalunya (IEEC), 08034 Barcelona, Spain

    Institut d'Estudis Espacials de Catalunya (IEEC), 08034 Barcelona, Spain

    Institut de Ciencies de l'Espai (ICE, CSIC), Campus UAB, Can Magrans s/n, 08193 Bellaterra, Spain

22. T. Bárczy
    Affiliation as printed

    Admatis, 5. Kandó Kálmán Street, 3534 Miskolc, Hungary

23. D. Barrado

    Centro de Astrobiología

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    Depto. de Astrofísica, Centro de Astrobiologia (CSIC-INTA), ESAC campus, 28692 Villanueva de la Cañada, Madrid, Spain

24. S. C. C. Barros

    Universidade do Porto · Institute of Astrophysics and Space Sciences · Centro de Astrofísica da Universidade do Porto

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    Departamento de Fisica e Astronomia, Faculdade de Ciencias, Universidade do Porto, Rua do Campo Alegre, 4169-007 Porto, Portugal

    Instituto de Astrofísica e Ciencias do Espaco, Universidade do Porto, CAUP, Rua das Estrelas, 4150-762 Porto, Portugal

25. W. Baumjohann

    Austrian Academy of Sciences · Space Research Institute

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    Space Research Institute, Austrian Academy of Sciences, Schmiedlstrasse 6, 8042 Graz, Austria

26. M. Beck

    University of Geneva

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    Observatoire Astronomique de l’Université de Genève, Chemin Pegasi 51, 1290 Versoix, Switzerland

    Observatoire Astronomique de l'Université de Genève, Chemin Pegasi 51, 1290 Versoix, Switzerland

27. T. Beck

    University of Bern

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    Physikalisches Institut, University of Bern, Sidlerstrasse 5, 3012 Bern, Switzerland

28. N. Billot

    University of Geneva

    Affiliation as printed

    Observatoire Astronomique de l’Université de Genève, Chemin Pegasi 51, 1290 Versoix, Switzerland

    Observatoire Astronomique de l'Université de Genève, Chemin Pegasi 51, 1290 Versoix, Switzerland

29. Xavier Bonfils

    Centre National de la Recherche Scientifique · Institut de Planétologie et d'Astrophysique de Grenoble · Université Grenoble Alpes

    Affiliation as printed

    Université Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France

30. A. Brandeker

    Stockholm University · AlbaNova

    Affiliation as printed

    Department of Astronomy, Stockholm University, AlbaNova University Center, 10691 Stockholm, Sweden

31. Christopher H. Broeg

    University of Bern · Center for Space and Habitability

    Affiliation as printed

    Center for Space and Habitability, University of Bern, Gesellschaftsstrasse 6, 3012 Bern, Switzerland

    Physikalisches Institut, University of Bern, Sidlerstrasse 5, 3012 Bern, Switzerland

32. J. Cabrera

    Deutsches Zentrum für Luft- und Raumfahrt e. V. (DLR)

    Affiliation as printed

    Institute of Planetary Research, German Aerospace Center (DLR), Rutherfordstrasse 2, 12489 Berlin, Germany

33. S. Charnoz

    Centre National de la Recherche Scientifique · Institut de physique du globe de Paris · Université Paris Cité

    Affiliation as printed

    Université de Paris, Institut de physique du globe de Paris, CNRS, 75005 Paris, France

34. Andrew Collier Cameron

    University of St Andrews

    Affiliation as printed

    Centre for Exoplanet Science, SUPA School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews KY16 9SS, UK

35. C. Corral van Damme

    European Space Agency · European Space Research and Technology Centre

    Affiliation as printed

    Science and Operations Department – Science Division (SCI-SC), Directorate of Science, European Space Agency (ESA), European Space Research and Technology Centre (ESTEC), Keplerlaan 1, 2201-AZ Noordwijk, The Netherlands

36. Sz. Csizmadia

    Deutsches Zentrum für Luft- und Raumfahrt e. V. (DLR)

    Affiliation as printed

    Institute of Planetary Research, German Aerospace Center (DLR), Rutherfordstrasse 2, 12489 Berlin, Germany

37. M. B. Davies

    Lund University

    Affiliation as printed

    Centre for Mathematical Sciences, Lund University, Box 118, 221 00 Lund, Sweden

38. M. Deleuil

    Centre National de la Recherche Scientifique · Aix-Marseille Université

    Affiliation as printed

    Aix-Marseille Univ., CNRS, CNES, LAM, 38 rue Frédéric Joliot-Curie, 13388 Marseille, France

39. L. Delrez

    University of Liège

    Affiliation as printed

    Astrobiology Research Unit, Université de Liège, Allée du 6 Août 19C, 4000 Liège, Belgium

    Space sciences, Technologies and Astrophysics Research (STAR) Institute, Université de Liège, Allée du 6 Août 19C, 4000 Liège, Belgium

40. Brice-Olivier Demory

    University of Bern · Center for Space and Habitability

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    Center for Space and Habitability, University of Bern, Gesellschaftsstrasse 6, 3012 Bern, Switzerland

41. A. Erikson

    Deutsches Zentrum für Luft- und Raumfahrt e. V. (DLR)

    Affiliation as printed

    Institute of Planetary Research, German Aerospace Center (DLR), Rutherfordstrasse 2, 12489 Berlin, Germany

42. J. Farinato

    Osservatorio Astronomico di Padova

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    INAF, Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, 35122 Padova, Italy

    INAF, Osservatorio Astronomico di Padova, Vicolo dell'Osservatorio 5, 35122 Padova, Italy

43. A. Fortier

    University of Bern · Center for Space and Habitability

    Affiliation as printed

    Center for Space and Habitability, University of Bern, Gesellschaftsstrasse 6, 3012 Bern, Switzerland

    Physikalisches Institut, University of Bern, Sidlerstrasse 5, 3012 Bern, Switzerland

44. L. Fossati

    Austrian Academy of Sciences · Space Research Institute

    Affiliation as printed

    Space Research Institute, Austrian Academy of Sciences, Schmiedlstrasse 6, 8042 Graz, Austria

45. Malcolm C. Fridlund Aachen Leiden Observatory

    Leiden University · Leiden Observatory · Chalmers University of Technology

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    Department of Space, Earth and Environment, Chalmers University of Technology, Onsala Space Observatory, 439 92 Onsala, Sweden

    Leiden Observatory, University of Leiden, PO Box 9513, 2300 RA Leiden, The Netherlands

46. D. Gandolfi

    University of Turin

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    Dipartimento di Fisica, Università degli Studi di Torino, via Pietro Giuria 1, 10125, Torino, Italy

47. M. Gillon

    University of Liège

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    Astrobiology Research Unit, Université de Liège, Allée du 6 Août 19C, 4000 Liège, Belgium

48. M. Güdel

    University of Vienna

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    University of Vienna, Department of Astrophysics, Türkenschanzstrasse 17, 1180 Vienna, Austria

49. S. Hoyer

    Centre National de la Recherche Scientifique · Aix-Marseille Université

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    Aix-Marseille Univ., CNRS, CNES, LAM, 38 rue Frédéric Joliot-Curie, 13388 Marseille, France

50. K. G. Isaak

    European Space Agency · European Space Research and Technology Centre

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    Science and Operations Department – Science Division (SCI-SC), Directorate of Science, European Space Agency (ESA), European Space Research and Technology Centre (ESTEC), Keplerlaan 1, 2201-AZ Noordwijk, The Netherlands

51. L. L. Kiss

    Eötvös Loránd University · Konkoly Observatory · HUN-REN Research Centre for Astronomy and Earth Sciences

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    ELTE Eötvös Loránd University, Institute of Physics, Pázmány Péter sétány 1/A, 1117, Hungary

    Konkoly Observatory, Research Centre for Astronomy and Earth Sciences, 1121 Budapest, Konkoly Thege Miklós út 15-17, Hungary

52. Emanuel Kopp

    Deutsches Zentrum für Luft- und Raumfahrt e. V. (DLR)

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    Institute of Optical Sensor Systems, German Aerospace Center (DLR), Rutherfordstrasse 2, 12489 Berlin, Germany

53. J. Laskar

    Centre National de la Recherche Scientifique · Observatoire de Paris · Institut de Mécanique Céleste et de Calcul des Éphémérides

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    IMCCE, UMR8028 CNRS, Observatoire de Paris, PSL Univ., Sorbonne Univ., 77 av. Denfert-Rochereau, 75014 Paris, France

54. Alain Lecavelier des Etangs

    Centre National de la Recherche Scientifique · Institut d'Astrophysique de Paris · Sorbonne Université

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    Institut d’astrophysique de Paris, UMR7095, CNRS, Sorbonne Université, 98bis blvd. Arago, 75014 Paris, France

    Institut d'astrophysique de Paris, UMR7095, CNRS, Sorbonne Université, 98bis blvd. Arago, 75014 Paris, France

55. Christophe Lovis

    University of Geneva

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    Observatoire Astronomique de l’Université de Genève, Chemin Pegasi 51, 1290 Versoix, Switzerland

    Observatoire Astronomique de l'Université de Genève, Chemin Pegasi 51, 1290 Versoix, Switzerland

56. Demetrio Magrin

    Osservatorio Astronomico di Padova

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    INAF, Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, 35122 Padova, Italy

    INAF, Osservatorio Astronomico di Padova, Vicolo dell'Osservatorio 5, 35122 Padova, Italy

57. Pierre F L Maxted

    Keele University

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    Astrophysics Group, Keele University, Staffordshire ST5 5BG, UK

58. M. Mečina

    University of Vienna

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    Department of Astrophysics, University of Vienna, Tuerkenschanzstrasse 17, 1180 Vienna, Austria

59. V. Nascimbeni

    Osservatorio Astronomico di Padova

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    INAF, Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, 35122 Padova, Italy

    INAF, Osservatorio Astronomico di Padova, Vicolo dell'Osservatorio 5, 35122 Padova, Italy

60. Göran Olofsson

    Stockholm University · AlbaNova

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    Department of Astronomy, Stockholm University, AlbaNova University Center, 10691 Stockholm, Sweden

61. R. Ottensamer

    University of Vienna

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    Department of Astrophysics, University of Vienna, Tuerkenschanzstrasse 17, 1180 Vienna, Austria

62. I. Pagano

    Osservatorio Astrofisico di Catania

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    INAF, Osservatorio Astrofísico di Catania, Via S. Sofia 78, 95123 Catania, Italy

63. Gisbert Peter

    Deutsches Zentrum für Luft- und Raumfahrt e. V. (DLR)

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    Institute of Optical Sensor Systems, German Aerospace Center (DLR), Rutherfordstrasse 2, 12489 Berlin, Germany

64. D. Piazza

    University of Bern

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    Physikalisches Institut, University of Bern, Sidlerstrasse 5, 3012 Bern, Switzerland

65. G. Piotto

    University of Padua · Osservatorio Astronomico di Padova

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    Dipartimento di Fisica e Astronomia “Galileo Galilei”, Universita degli Studi di Padova, Vicolo dell’Osservatorio 3, 35122 Padova, Italy

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    Dipartimento di Fisica e Astronomia "Galileo Galilei", Universita degli Studi di Padova, Vicolo dell'Osservatorio 3, 35122 Padova, Italy

    INAF, Osservatorio Astronomico di Padova, Vicolo dell'Osservatorio 5, 35122 Padova, Italy

66. D. Pollacco

    University of Warwick

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    Department of Physics, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK

67. Didier P. Queloz

    University of Cambridge · ETH Zurich

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    Cavendish Laboratory, JJ Thomson Avenue, Cambridge CB3 0HE, UK

    ETH Zurich, Department of Physics, Wolfgang-Pauli-Strasse 2, 8093 Zurich, Switzerland

68. Roberto Ragazzoni

    University of Padua · Osservatorio Astronomico di Padova

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    Dipartimento di Fisica e Astronomia “Galileo Galilei”, Universita degli Studi di Padova, Vicolo dell’Osservatorio 3, 35122 Padova, Italy

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    Dipartimento di Fisica e Astronomia "Galileo Galilei", Universita degli Studi di Padova, Vicolo dell'Osservatorio 3, 35122 Padova, Italy

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69. N. Rando

    European Space Agency · European Space Research and Technology Centre

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    ESTEC, European Space Agency, 2201AZ, Noordwijk, The Netherlands

70. Heike Rauer

    Deutsches Zentrum für Luft- und Raumfahrt e. V. (DLR) · Technische Universität Berlin · Freie Universität Berlin

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    Institut für Geologische Wissenschaften, Freie Universität Berlin, 12249 Berlin, Germany

    Institute of Planetary Research, German Aerospace Center (DLR), Rutherfordstrasse 2, 12489 Berlin, Germany

    Zentrum für Astronomie und Astrophysik, Technische Universität Berlin, Hardenbergstr. 36, 10623 Berlin, Germany

71. I. Ribas

    Institute of Space Sciences · Institut d'Estudis Espacials de Catalunya

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    Institut de Ciencies de l’Espai (ICE, CSIC), Campus UAB, Can Magrans s/n, 08193 Bellaterra, Spain

    Institut d’Estudis Espacials de Catalunya (IEEC), 08034 Barcelona, Spain

    Institut d'Estudis Espacials de Catalunya (IEEC), 08034 Barcelona, Spain

    Institut de Ciencies de l'Espai (ICE, CSIC), Campus UAB, Can Magrans s/n, 08193 Bellaterra, Spain

72. G. Scandariato

    Osservatorio Astrofisico di Catania

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    INAF, Osservatorio Astrofísico di Catania, Via S. Sofia 78, 95123 Catania, Italy

73. Damien Ségransan

    University of Geneva

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    Observatoire Astronomique de l’Université de Genève, Chemin Pegasi 51, 1290 Versoix, Switzerland

    Observatoire Astronomique de l'Université de Genève, Chemin Pegasi 51, 1290 Versoix, Switzerland

74. A. E. Simon

    University of Bern

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    Physikalisches Institut, University of Bern, Sidlerstrasse 5, 3012 Bern, Switzerland

75. Alexis M. S. Smith

    Deutsches Zentrum für Luft- und Raumfahrt e. V. (DLR)

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    Institute of Planetary Research, German Aerospace Center (DLR), Rutherfordstrasse 2, 12489 Berlin, Germany

76. M. Steller

    Austrian Academy of Sciences · Space Research Institute

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    Space Research Institute, Austrian Academy of Sciences, Schmiedlstrasse 6, 8042 Graz, Austria

77. Gy. M. Szabó

    Eötvös Loránd University

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    ELTE Eötvös Loránd University, Gothard Astrophysical Observatory, 9700 Szombathely, Szent Imre h. u. 112, Hungary

    MTA-ELTE Exoplanet Research Group, 9700 Szombathely, Szent Imre h. u. 112, Hungary

78. N. Thomas

    University of Bern

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    Physikalisches Institut, University of Bern, Sidlerstrasse 5, 3012 Bern, Switzerland

79. Stéphane Udry

    University of Geneva

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    Observatoire Astronomique de l’Université de Genève, Chemin Pegasi 51, 1290 Versoix, Switzerland

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80. V. Van Grootel

    University of Liège

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    Space sciences, Technologies and Astrophysics Research (STAR) Institute, Université de Liège, Allée du 6 Août 19C, 4000 Liège, Belgium

81. N. A. Walton

    University of Cambridge

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    Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK