Issue |
A&A
Volume 659, March 2022
|
|
---|---|---|
Article Number | L4 | |
Number of page(s) | 8 | |
Section | Letters to the Editor | |
DOI | https://doi.org/10.1051/0004-6361/202243082 | |
Published online | 02 March 2022 |
Letter to the Editor
CHEOPS geometric albedo of the hot Jupiter HD 209458 b⋆
1
Department of Astronomy, Stockholm University, AlbaNova University Center, 10691 Stockholm, Sweden
e-mail: alexis@astro.su.se
2
Center for Space and Habitability, Gesellsschaftstrasse 6, 3012 Bern, Switzerland
3
Department of Physics, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK
4
Observatoire Astronomique de l’Université de Genève, Chemin Pegasi 51, Versoix, Switzerland
5
Physikalisches Institut, University of Bern, Gesellsschaftstrasse 6, 3012 Bern, Switzerland
6
Aix Marseille Univ, CNRS, CNES, LAM, 38 rue Frédéric Joliot-Curie, 13388 Marseille, France
7
Division Technique INSU, BP 330, 83507 La Seyne cedex, France
8
Astrophysics Group, Keele University, Staffordshire ST5 5BG, UK
9
Instituto de Astrofisica e Ciencias do Espaco, Universidade do Porto, CAUP, Rua das Estrelas, 4150-762 Porto, Portugal
10
Departamento de Fisica e Astronomia, Faculdade de Ciencias, Universidade do Porto, Rua do Campo Alegre, 4169-007 Porto, Portugal
11
Astrobiology Research Unit, Université de Liège, Allée du 6 Août 19C, 4000 Liège, Belgium
12
Space sciences, Technologies and Astrophysics Research (STAR) Institute, Université de Liège, Allée du 6 Aoút 19C, 4000 Liège, Belgium
13
INAF, Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, 35122 Padova, Italy
14
Instituto de Astrofisica de Canarias, 38200 La Laguna, Tenerife, Spain
15
Departamento de Astrofisica, Universidad de La Laguna, 38206 La Laguna, Tenerife, Spain
16
Institut de Ciencies de l’Espai (ICE, CSIC), Campus UAB, Can Magrans s/n, 08193 Bellaterra, Spain
17
Institut d’Estudis Espacials de Catalunya (IEEC), 08034 Barcelona, Spain
18
Admatis, 5. Kandó Kálmán Street, 3534 Miskolc, Hungary
19
Depto. de Astrofisica, Centro de Astrobiologia (CSIC-INTA), ESAC campus, 28692 Villanueva de la Cañada, Madrid, Spain
20
Space Research Institute, Austrian Academy of Sciences, Schmiedlstrasse 6, 8042 Graz, Austria
21
Université Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France
22
Institute of Planetary Research, German Aerospace Center (DLR), Rutherfordstrasse 2, 12489 Berlin, Germany
23
Université de Paris, Institut de physique du globe de Paris, CNRS, 75005 Paris, France
24
Centre for Exoplanet Science, SUPA School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews KY16 9SS, UK
25
ESTEC, European Space Agency, 2201 AZ Noordwijk, The Netherlands
26
Centre for Mathematical Sciences, Lund University, Box 118, 221 00 Lund, Sweden
27
Leiden Observatory, University of Leiden, PO Box 9513, 2300 RA Leiden, The Netherlands
28
Department of Space, Earth and Environment, Chalmers University of Technology, Onsala Space Observatory, 43992 Onsala, Sweden
29
Dipartimento di Fisica, Universita degli Studi di Torino, Via Pietro Giuria 1, 10125 Torino, Italy
30
University of Vienna, Department of Astrophysics, Türkenschanzstrasse 17, 1180 Vienna, Austria
31
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
32
Konkoly Observatory, Research Centre for Astronomy and Earth Sciences, 1121 Budapest Konkoly Thege Miklós út 15-17, Hungary
33
ELTE Eötvös Loránd University, Institute of Physics, Pázmány Péter sétány 1/A, 1117 Budapest, Hungary
34
IMCCE, UMR8028 CNRS, Observatoire de Paris, PSL Univ., Sorbonne Univ., 77 av. Denfert-Rochereau, 75014 Paris, France
35
Institut d’astrophysique de Paris, UMR7095 CNRS, Université Pierre & Marie Curie, 98bis blvd. Arago, 75014 Paris, France
36
Department of Astrophysics, University of Vienna, Tuerkenschanzstrasse 17, 1180 Vienna, Austria
37
INAF, Osservatorio Astrofisico di Catania, Via S. Sofia 78, 95123 Catania, Italy
38
Institute of Optical Sensor Systems, German Aerospace Center (DLR), Rutherfordstrasse 2, 12489 Berlin, Germany
39
Dipartimento di Fisica e Astronomia “Galileo Galilei”, Universita degli Studi di Padova, Vicolo dell’Osservatorio 3, 35122 Padova, Italy
40
Cavendish Laboratory, JJ Thomson Avenue, Cambridge CB3 0HE, UK
41
ETH Zürich, Department of Physics, Wolfgang-Pauli-Strasse 27, 8093 Zürich, Switzerland
42
Center for Astronomy and Astrophysics, Technical University Berlin, Hardenberstrasse 36, 10623 Berlin, Germany
43
Institut für Geologische Wissenschaften, Freie Universität Berlin, 12249 Berlin, Germany
44
ELTE Eötvös Loránd University, Gothard Astrophysical Observatory, 9700 Szombathely, Szent Imre h. u. 112, Hungary
45
MTA-ELTE Exoplanet Research Group, 9700 Szombathely, Szent Imre h. u. 112, Hungary
46
MTA-ELTE Lendület “Momentum” Milky Way Research Group, Szombathely, Hungary
47
Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK
Received:
9
January
2022
Accepted:
16
February
2022
We report the detection of the secondary eclipse of the hot Jupiter HD 209458 b in optical/visible light using the CHEOPS space telescope. Our measurement of 20.4−3.3+3.2 parts per million translates into a geometric albedo of Ag = 0.096 ± 0.016. The previously estimated dayside temperature of about 1500 K implies that our geometric albedo measurement consists predominantly of reflected starlight and is largely uncontaminated by thermal emission. This makes the present result one of the most robust measurements of Ag for any exoplanet. Our calculations of the bandpass-integrated geometric albedo demonstrate that the measured value of Ag is consistent with a cloud-free atmosphere, where starlight is reflected via Rayleigh scattering by hydrogen molecules, and the water and sodium abundances are consistent with stellar metallicity. We predict that the bandpass-integrated TESS geometric albedo is too faint to detect and that a phase curve of HD 209458 b observed by CHEOPS would have a distinct shape associated with Rayleigh scattering if the atmosphere is indeed cloud free.
Key words: techniques: photometric / planetary systems / planets and satellites: atmospheres / planets and satellites: individual: HD 209458 b
The raw and detrended photometric time-series data are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/659/L4
© ESO 2022
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