Planetary systems; Planets; Planets and satellites: Atmospheres; Satellites: Individual: HD 209458 b; Techniques: Photometric; Band pass; Geometric albedos; Jupiters; Measurements of; Optical-; Planetary system; Planets and satellites: atmospheres; Satellite: individual: HD 209458 b; Secondary eclipse; Techniques: photometric; Astronomy and Astrophysics; Space and Planetary Science; astro-ph.EP
Abstract :
[en] 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+3.2-3.3 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.
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Brandeker, A. ; Department of Astronomy, Stockholm University, AlbaNova University Center, Stockholm, Sweden
Heng, K. ; Center for Space and Habitability, Bern, Switzerland ; Department of Physics, University of Warwick, Coventry, United Kingdom
Lendl, Monika ; Université de Liège - ULiège > Département d'astrophysique, géophysique et océanographie (AGO) > Origines Cosmologiques et Astrophysiques (OrCa) ; Observatoire Astronomique de l’Université de Genève, Versoix, Switzerland
Patel, J.A. ; Department of Astronomy, Stockholm University, AlbaNova University Center, Stockholm, Sweden
Morris, B.M.; Center for Space and Habitability, Bern, Switzerland
Broeg, C.; Center for Space and Habitability, Bern, Switzerland ; Physikalisches Institut, University of Bern, Bern, Switzerland
Guterman, P.; Aix Marseille Univ, CNRS, CNES, LAM, Marseille, France ; Division Technique INSU, France
Beck, M.; Observatoire Astronomique de l’Université de Genève, Versoix, Switzerland
Maxted, P.F.L. ; Astrophysics Group, Keele University, Staffordshire, United Kingdom
Demangeon, O. ; Instituto de Astrofisica e Ciencias do Espaco, Universidade do Porto, CAUP, Porto, Portugal ; Departamento de Fisica e Astronomia, Faculdade de Ciencias, Universidade do Porto, Porto, Portugal
Demory, B.-O. ; Center for Space and Habitability, Bern, Switzerland
Kitzmann, D.; Center for Space and Habitability, Bern, Switzerland
Santos, N.C.; Instituto de Astrofisica e Ciencias do Espaco, Universidade do Porto, CAUP, Porto, Portugal ; Departamento de Fisica e Astronomia, Faculdade de Ciencias, Universidade do Porto, Porto, Portugal
Singh, V.; INAF, Osservatorio Astronomico di Padova, Padova, Italy
Alibert, Y.; Physikalisches Institut, University of Bern, Bern, Switzerland
Alonso, R.; Instituto de Astrofisica de Canarias, Tenerife, Spain ; Departamento de Astrofisica, Universidad de La Laguna, Tenerife, Spain
Anglada, G.; Institut de Ciencies de l’Espai (ICE, CSIC), Campus UAB, Bellaterra, Spain ; Institut d’Estudis Espacials de Catalunya (IEEC), Barcelona, Spain
Bárczy, T.; Admatis, Miskolc, Hungary
Barrado y Navascues, D.; Depto. de Astrofisica, Centro de Astrobiologia (CSIC-INTA), ESAC Campus, Madrid, Spain
Barros, S.C.C.; Instituto de Astrofisica e Ciencias do Espaco, Universidade do Porto, CAUP, Porto, Portugal ; Departamento de Fisica e Astronomia, Faculdade de Ciencias, Universidade do Porto, Porto, Portugal
Baumjohann, W.; Space Research Institute, Austrian Academy of Sciences, Graz, Austria
Beck, T.; Physikalisches Institut, University of Bern, Bern, Switzerland
Benz, W.; Center for Space and Habitability, Bern, Switzerland ; Physikalisches Institut, University of Bern, Bern, Switzerland
Billot, N.; Observatoire Astronomique de l’Université de Genève, Versoix, Switzerland
Bonfils, X.; Université Grenoble Alpes, CNRS, IPAG, Grenoble, France
Bruno, G.; Physikalisches Institut, University of Bern, Bern, Switzerland
Cabrera, J.; Institute of Planetary Research, German Aerospace Center (DLR), Berlin, Germany
Charnoz, S.; Université de Paris, Institut de Physique du Globe de Paris, CNRS, Paris, France
Collier Cameron, A.; Centre for Exoplanet Science, SUPA School of Physics and Astronomy, University of St Andrews, St Andrews, United Kingdom
Corral van Damme, C.; ESTEC, European Space Agency, Noordwijk, Netherlands
Csizmadia, Sz.; Institute of Planetary Research, German Aerospace Center (DLR), Berlin, Germany
Davies, M.B.; Centre for Mathematical Sciences, Lund University, Lund, Sweden
Deleuil, M.; Aix Marseille Univ, CNRS, CNES, LAM, Marseille, France
Deline, A.; Observatoire Astronomique de l’Université de Genève, Versoix, Switzerland
Ehrenreich, D.; Observatoire Astronomique de l’Université de Genève, Versoix, Switzerland
Erikson, A.; Institute of Planetary Research, German Aerospace Center (DLR), Berlin, Germany
Farinato, J.; INAF, Osservatorio Astronomico di Padova, Padova, Italy
Fortier, A.; Center for Space and Habitability, Bern, Switzerland ; Physikalisches Institut, University of Bern, Bern, Switzerland
Fossati, L.; Space Research Institute, Austrian Academy of Sciences, Graz, Austria
Fridlund, M.; Leiden Observatory, University of Leiden, Leiden, Netherlands ; Department of Space, Earth and Environment, Chalmers University of Technology, Onsala Space Observatory, Onsala, Sweden
Gandolfi, D.; Dipartimento di Fisica, Universita degli Studi di Torino, Torino, Italy
Güdel, M.; University of Vienna, Department of Astrophysics, Vienna, Austria
Hoyer, S.; Aix Marseille Univ, CNRS, CNES, LAM, Marseille, France
Isaak, K.G.; Science and Operations Department – Science Division (SCI-SC), Directorate of Science, European Space Agency (ESA), European Space Research and Technology Centre (ESTEC), Noordwijk, Netherlands
Kiss, L.; Konkoly Observatory, Research Centre for Astronomy and Earth Sciences, Hungary ; ELTE Eötvös Loránd University, Institute of Physics, Budapest, Hungary
Laskar, J.; IMCCE, UMR8028 CNRS, Observatoire de Paris, PSL Univ., Sorbonne Univ., Paris, France
Lecavelier des Etangs, A.; Institut d’Astrophysique de Paris, UMR7095 CNRS, Université Pierre & Marie Curie, Paris, France
Lovis, C.; Observatoire Astronomique de l’Université de Genève, Versoix, Switzerland
Luntzer, A.; Department of Astrophysics, University of Vienna, Vienna, Austria
Magrin, D.; INAF, Osservatorio Astronomico di Padova, Padova, Italy
Nascimbeni, V.; INAF, Osservatorio Astronomico di Padova, Padova, Italy
Olofsson, G.; Department of Astronomy, Stockholm University, AlbaNova University Center, Stockholm, Sweden
Ottensamer, R.; Department of Astrophysics, University of Vienna, Vienna, Austria
Pagano, I.; INAF, Osservatorio Astrofisico di Catania, Catania, Italy
Pallé, E.; Instituto de Astrofisica de Canarias, Tenerife, Spain
Peter, G.; Institute of Optical Sensor Systems, German Aerospace Center (DLR), Berlin, Germany
Piotto, G.; INAF, Osservatorio Astronomico di Padova, Padova, Italy ; Dipartimento di Fisica e Astronomia “Galileo Galilei”, Universita degli Studi di Padova, Padova, Italy
Pollacco, D.; Department of Physics, University of Warwick, Coventry, United Kingdom
Queloz, D.; Cavendish Laboratory, Cambridge, United Kingdom ; ETH Zürich, Department of Physics, Zürich, Switzerland
Ragazzoni, R.; INAF, Osservatorio Astronomico di Padova, Padova, Italy ; Dipartimento di Fisica e Astronomia “Galileo Galilei”, Universita degli Studi di Padova, Padova, Italy
Rando, N.; ESTEC, European Space Agency, Noordwijk, Netherlands
Rauer, H.; Institute of Planetary Research, German Aerospace Center (DLR), Berlin, Germany ; Center for Astronomy and Astrophysics, Technical University Berlin, Berlin, Germany ; Institut für Geologische Wissenschaften, Freie Universität Berlin, Berlin, Germany
Ribas, I.; Institut de Ciencies de l’Espai (ICE, CSIC), Campus UAB, Bellaterra, Spain ; Institut d’Estudis Espacials de Catalunya (IEEC), Barcelona, Spain
Scandariato, G.; INAF, Osservatorio Astrofisico di Catania, Catania, Italy
Ségransan, D.; Observatoire Astronomique de l’Université de Genève, Versoix, Switzerland
Simon, A.E.; Physikalisches Institut, University of Bern, Bern, Switzerland
Smith, A.M.S.; Institute of Planetary Research, German Aerospace Center (DLR), Berlin, Germany
Sousa, S.G.; Instituto de Astrofisica e Ciencias do Espaco, Universidade do Porto, CAUP, Porto, Portugal
Steller, M.; Space Research Institute, Austrian Academy of Sciences, Graz, Austria
Szabó, Gy. M.; ELTE Eötvös Loránd University, Gothard Astrophysical Observatory, Hungary ; MTA-ELTE Exoplanet Research Group, Hungary ; MTA-ELTE Lendület “Momentum” Milky Way Research Group, Szombathely, Hungary
Thomas, N.; Physikalisches Institut, University of Bern, Bern, Switzerland
Udry, S.; Observatoire Astronomique de l’Université de Genève, Versoix, Switzerland
Van Grootel, Valérie ; Université de Liège - ULiège > Unités de recherche interfacultaires > Space sciences, Technologies and Astrophysics Research (STAR)
Walton, N.; Institute of Astronomy, University of Cambridge, Cambridge, United Kingdom
Wolter, D.; Institute of Planetary Research, German Aerospace Center (DLR), Berlin, Germany
Acknowledgements. CHEOPS is an ESA mission in partnership with Switzerland with important contributions to the payload and the ground segment from Austria, Belgium, France, Germany, Hungary, Italy, Portugal, Spain, Sweden, and the United Kingdom. The CHEOPS Consortium would like to gratefully acknowledge the support received by all the agencies, offices, universities, and industries involved. Their flexibility and willingness to explore new approaches were essential to the success of this mission. KGI is the ESA CHEOPS Project Scientist and is responsible for the ESA CHEOPS Guest Observers Programme. She does not participate in, or contribute to, the definition of the Guaranteed Time Programme of the CHEOPS mission through which observations described in this paper have been taken, nor to any aspect of target selection for the programme. This research has made use of the SVO Filter Profile Ser- vice (http://svo2.cab.inta-csic.es/theory/fps/) supported from the Spanish MINECO through grant AYA2017-84089. We used matplotlib (Hunter 2007) for the figures. A.Br. was supported by the SNSA. P.F.L.M. acknowledges support from STFC research grant number ST/M001040/1. This work was supported by FCT – Fundação para a Ciáncia e a Tecnologia through national funds and by FEDER through COMPETE2020 – Programa Operacional Competitividade e Internacionalizacão by these grants: UID/FIS/04434/2019, UIDB/04434/2020, UIDP/04434/2020, PTDC/FIS-AST/32113/2017 and POCI-01-0145-FEDER-032113, PTDC/FIS-AST/28953/2017 and POCI-01-0145-FEDER-028953, PTDC/FIS-AST/28987/2017 and POCI-01-0145-FEDER-028987, O.D.S.D. is supported in the form of work contract (DL 57/2016/CP1364/CT0004) funded by national funds through FCT. L.D. is an F.R.S.-FNRS Postdoctoral Researcher. The Belgian participation to CHEOPS has been supported by the Belgian Federal Science Policy Office (BELSPO) in the framework of the PRODEX Program, and by the University of Liège through an ARC grant for Concerted Research Actions financed by the Wallonia-Brussels Federation. B.-O.D. acknowledges support from the Swiss National Science Foundation (PP00P2-190080). Y.A. and M.J.H. acknowledge the support of the Swiss National Fund under grant 200020_172746. We acknowledge support from the Spanish Ministry of Science and Innovation and the European Regional Development Fund through grants ESP2016-80435-C2-1-R, ESP2016-80435-C2-2-R, PGC2018-098153-B-C33, PGC2018-098153-B-C31, ESP2017-87676-C5-1-R, MDM-2017-0737 Unidad de Excelencia Maria de Maeztu-Centro de Astrobiología (INTA-CSIC), as well as the support of the Generalitat de Catalunya/CERCA programme. The MOC activities have been supported by the ESA contract No. 4000124370. S.C.C.B. acknowledges support from FCT through FCT contracts nr. IF/01312/2014/CP1215/CT0004. X.B., S.C., D.G., M.F., and J.L. acknowledge their role as ESA-appointed CHEOPS science team members. This project was supported by the CNES. This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (project Four Aces. grant agreement No 724427). It has also been carried out in the frame of the National Centre for Competence in Research PlanetS supported by the Swiss National Science Foundation (SNSF). D.E. acknowledges financial support from the Swiss National Science Foundation for project 200021_200726. M.F. was supported by SNSA (DNR 65/19, 174/18). D.G. was supported by the CRT foundation under Grant No. 2018.2323 “Gaseous or rocky? Unveiling the nature of small worlds”. M.G. is an F.R.S.-FNRS Senior Research Associate. S.H. gratefully acknowledges CNES funding through the grant 837319. K.G.I. is the ESA CHEOPS Project Scientist and is responsible for the ESA CHEOPS Guest Observers Programme. She does not participate in, or contribute to, the definition of the Guaranteed Time Programme of the CHEOPS mission through which observations described in this paper have been taken, nor to any aspect of target selection for the programme. This work was granted access to the HPC resources of MesoPSL financed by the Region Ile de France and the project Equip@Meso (reference ANR-10-EQPX-29-01) of the programmeInvestissements d’Avenir supervised by the Agence Nationale pour la Recherche. This work was partially supported by a grant from the Simons Foundation (PI Queloz, grant number 327127). S.G.S. acknowledges support from FCT through FCT contract nr. CEECIND/00826/2018 and POPH/FSE (EC). This project has been supported by the Hungarian National Research, Development and Innovation Office (NKFIH) grants GINOP-2.3.2-15-2016-00003, K-119517, K-125015, and the City of Szombathely under Agreement No. 67.177-21/2016. V.V.G. is an F.R.S-FNRS Research Associate.CHEOPS is an ESA mission in partnership with Switzerland with important contributions to the payload and the ground segment from Austria, Belgium, France, Germany, Hungary, Italy, Portugal, Spain, Sweden, and the United Kingdom. The CHEOPS Consortium would like to gratefully acknowledge the support received by all the agencies, offices, universities, and industries involved. Their flexibility and willingness to explore new approaches were essential to the success of this mission. KGI is the ESA CHEOPS Project Scientist and is responsible for the ESA CHEOPS Guest Observers Programme. She does not participate in, or contribute to, the definition of the Guaranteed Time Programme of the CHEOPS mission through which observations described in this paper have been taken, nor to any aspect of target selection for the programme. This research has made use of the SVO Filter Profile Service (http://svo2.cab.inta-csic.es/theory/fps/) supported from the Spanish MINECO through grant AYA2017-84089. We used matplotlib (Hunter 2007) for the figures. A.Br. was supported by the SNSA. P.F.L.M. acknowledges support from STFC research grant number ST/M001040/1. This work was supported by FCT ? Funda??o para a Ci?ncia e a Tecnologia through national funds and by FEDER through COMPETE2020 ? Programa Operacional Competitividade e Internacionalizac?o by these grants: UID/FIS/04434/2019, UIDB/04434/2020, UIDP/04434/2020, PTDC/FIS-AST/32113/2017 and POCI-01-0145-FEDER-032113, PTDC/FIS-AST/28953/2017 and POCI-01-0145-FEDER-028953, PTDC/FIS-AST/28987/2017 and POCI-01-0145-FEDER-028987, O.D.S.D. is supported in the form of work contract (DL 57/2016/CP1364/CT0004) funded by national funds through FCT. L.D. is an F.R.S.-FNRS Postdoctoral Researcher. The Belgian participation to CHEOPS has been supported by the Belgian Federal Science Policy Office (BELSPO) in the framework of the PRODEX Program, and by the University of Li?ge through an ARC grant for Concerted Research Actions financed by the Wallonia-Brussels Federation. B.-O.D. acknowledges support from the Swiss National Science Foundation (PP00P2-190080). Y.A. and M.J.H. acknowledge the support of the Swiss National Fund under grant 200020_172746. We acknowledge support from the Spanish Ministry of Science and Innovation and the European Regional Development Fund through grants ESP2016-80435-C2-1-R, ESP2016-80435-C2-2-R, PGC2018-098153-B-C33, PGC2018-098153-B-C31, ESP2017-87676-C5-1-R, MDM-2017-0737 Unidad de Excelencia Maria de Maeztu-Centro de Astrobiolog?a (INTA-CSIC), as well as the support of the Generalitat de Catalunya/CERCA programme. The MOC activities have been supported by the ESA contract No. 4000124370. S.C.C.B. acknowledges support from FCT through FCT contracts nr. IF/01312/2014/CP1215/CT0004. X.B., S.C., D.G., M.F., and J.L. acknowledge their role as ESA-appointed CHEOPS science team members. This project was supported by the CNES. This project has received funding from the European Research Council (ERC) under the European Union?s Horizon 2020 research and innovation programme (project Four Aces. grant agreement No 724427). It has also been carried out in the frame of the National Centre for Competence in Research PlanetS supported by the Swiss National Science Foundation (SNSF). D.E. acknowledges financial support from the Swiss National Science Foundation for project 200021_200726. M.F. was supported by SNSA (DNR 65/19, 174/18). D.G. was supported by the CRT foundation under Grant No. 2018.2323 ?Gaseous or rocky? Unveiling the nature of small worlds?. M.G. is an F.R.S.-FNRS Senior Research Associate. S.H. gratefully acknowledges CNES funding through the grant 837319. K.G.I. is the ESA CHEOPS Project Scientist and is responsible for the ESA CHEOPS Guest Observers Programme. She does not participate in, or contribute to, the definition of the Guaranteed Time Programme of the CHEOPS mission through which observations described in this paper have been taken, nor to any aspect of target selection for the programme. This work was granted access to the HPC resources of MesoPSL financed by the Region Ile de France and the project Equip@Meso (reference ANR-10-EQPX-29-01) of the programme Investissements d?Avenir supervised by the Agence Nationale pour la Recherche. This work was partially supported by a grant from the Simons Foundation (PI Queloz, grant number 327127). S.G.S. acknowledges support from FCT through FCT contract nr. CEECIND/00826/2018 and POPH/FSE (EC). This project has been supported by the Hungarian National Research, Development and Innovation Office (NKFIH) grants GINOP-2.3.2-15-2016-00003, K-119517, K-125015, and the City of Szombathely under Agreement No. 67.177-21/2016. V.V.G. is an F.R.S-FNRS Research Associate.
