Planets and satellites: Individual: 55 Cnc e; Stars: Individual: 55 Cnc; Techniques: Photometric; Circumstellar; Exo-planets; Optical range; Planet and satellite: individual: 55 cnc e; Planets and satellites: individual; Short periods; Stars: individual: 55 cnc; Techniques: photometric; Time variable; Time-scales; Astronomy and Astrophysics; Space and Planetary Science; astro-ph.EP
Abstract :
[en] Context. 55 Cnc e is an ultra-short period super-Earth transiting a Sun-like star. Previous observations in the optical range detected a time-variable flux modulation that is phased with the planetary orbital period, whose amplitude is too large to be explained by reflected light and thermal emission alone. Aims. The goal of the study is to investigate the origin of the variability and timescale of the phase-curve modulation in 55 Cnc e. To this end, we used the CHaracterising ExOPlanet Satellite (CHEOPS), whose exquisite photometric precision provides an opportunity to characterise minute changes in the phase curve from one orbit to the next. Methods. CHEOPS observed 29 individual visits of 55 Cnc e between March 2020 and February 2022. Based on these observations, we investigated the different processes that could be at the origin of the observed modulation. In particular, we built a toy model to assess whether a circumstellar torus of dust driven by radiation pressure and gravity might match the observed flux variability timescale. Results. We find that the phase-curve amplitude and peak offset of 55 Cnc e do vary between visits. The sublimation timescales of selected dust species reveal that silicates expected in an Earth-like mantle would not survive long enough to explain the observed phase-curve modulation. We find that silicon carbide, quartz, and graphite are plausible candidates for the circumstellar torus composition because their sublimation timescales are long. Conclusions. The extensive CHEOPS observations confirm that the phase-curve amplitude and offset vary in time. We find that dust could provide the grey opacity source required to match the observations. However, the data at hand do not provide evidence that circumstellar material with a variable grain mass per unit area causes the observed variability. Future observations with the James Webb Space Telescope (JWST) promise exciting insights into this iconic super-Earth.
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Meier Valdés, E.A. ; Center for Space and Habitability, University of Bern, Bern, Switzerland
Morris, B.M.; Space Telescope Science Institute, Baltimore, United States
Demory, B.-O.; Center for Space and Habitability, University of Bern, Bern, Switzerland ; Physikalisches Institut, University of Bern, Bern, Switzerland
Brandeker, A.; Department of Astronomy, Stockholm University, AlbaNova University Center, Stockholm, Sweden
Kitzmann, D.; Center for Space and Habitability, University of Bern, Bern, Switzerland
Benz, W.; Center for Space and Habitability, University of Bern, Bern, Switzerland ; Physikalisches Institut, University of Bern, Bern, Switzerland
Deline, A.; Observatoire Astronomique de l'Université de Genève, Versoix, Switzerland
Florén, H.-G.; Department of Astronomy, Stockholm University, AlbaNova University Center, Stockholm, Sweden
Sousa, S.G.; Instituto de Astrofisica e Ciencias do Espaco, Universidade do Porto, CAUP, Porto, Portugal
Bourrier, V.; Observatoire Astronomique de l'Université de Genève, Versoix, Switzerland
Singh, V.; INAF, Osservatorio Astrofisico di Catania, Catania, Italy
Heng, K.; Ludwig Maximilian University, University Observatory Munich, Munich, Germany ; University of Warwick, Department of Physics, Astronomy & Astrophysics Group, Coventry, United Kingdom ; University of Bern, ARTORG Center for Biomedical Engineering Research, Bern, Switzerland
Strugarek, A.; Université Paris-Saclay, Université Paris Cité, CEA, CNRS, AIM, Gif-sur-Yvette, France
Bower, D.J.; Center for Space and Habitability, University of Bern, Bern, Switzerland
Jäggi, N.; Physikalisches Institut, University of Bern, Bern, Switzerland
Carone, L.; Space Research Institute, Austrian Academy of Sciences, Graz, Austria
Lendl, M.; Observatoire Astronomique de l'Université de Genève, Versoix, Switzerland
Jones, K.; Center for Space and Habitability, University of Bern, Bern, Switzerland
Oza, A.V.; Jet Propulsion Laboratory, California Institute of Technology, Pasadena, United States
Demangeon, O.D.S.; 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
Alibert, Y.; Physikalisches Institut, University of Bern, Bern, Switzerland
Alonso, R.; Instituto de Astrofisica de Canarias, La Laguna, Spain ; Departamento de Astrofisica, Universidad de La Laguna, La Laguna, Spain
Anglada, G.; Institut de Ciencies de l'Espai (ICE CSIC), Bellaterra, Spain ; Institut d'Estudis Espacials de Catalunya (IEEC), Barcelona, Spain
Asquier, J.; European Space Agency (ESA), European Space Research and Technology Centre (ESTEC), Noordwijk, Netherlands
Bárczy, T.; Admatis, Miskolc, Hungary
Barrado Navascues, D.; Depto. de Astrofisica, Centro de Astrobiologia (CSIC-INTA), 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, M.; Observatoire Astronomique de l'Université de Genève, Versoix, Switzerland
Beck, T.; 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
Borsato, L.; INAF, Osservatorio Astronomico di Padova, Padova, Italy
Broeg, C.; Center for Space and Habitability, University of Bern, Bern, Switzerland ; 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
Csizmadia, Sz.; Institute of Planetary Research, German Aerospace Center (DLR), Berlin, Germany
Cubillos, P.E.; Space Research Institute, Austrian Academy of Sciences, Graz, Austria ; INAF, Osservatorio Astrofisico di Torino, Pino Torinese, Italy
Davies, M.B.; Centre for Mathematical Sciences, Lund University, Lund, Sweden
Deleuil, M.; Aix Marseille Univ, CNRS, CNES, LAM, Marseille, France
Delrez, Laetitia ; Université de Liège - ULiège > Département d'astrophysique, géophysique et océanographie (AGO) > Exoplanets in Transit: Identification and Characterization
Ehrenreich, D.; Observatoire Astronomique de l'Université de Genève, Versoix, Switzerland ; Centre Vie dans l'Univers, Faculté des sciences, Université de Genève, Genève 4, Switzerland
Erikson, A.; Institute of Planetary Research, German Aerospace Center (DLR), Berlin, Germany
Fortier, A.; Center for Space and Habitability, University of Bern, 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, Sweden
Gandolfi, D.; Dipartimento di Fisica, Universita degli Studi di Torino, Torino, Italy
Gillon, Michaël ; Université de Liège - ULiège > Département d'astrophysique, géophysique et océanographie (AGO)
Güdel, M.; Department of Astrophysics, University of Vienna, Vienna, Austria
Günther, M.N.; European Space Agency (ESA), European Space Research and Technology Centre (ESTEC), Noordwijk, Netherlands
Hoyer, S.; Aix Marseille Univ, CNRS, CNES, LAM, Marseille, France
Isaak, K.G.; European Space Agency (ESA), European Space Research and Technology Centre (ESTEC), Noordwijk, Netherlands
Kiss, L.L.; Konkoly Observatory, Research Centre for Astronomy and Earth Sciences, Budapest, 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
Magrin, D.; INAF, Osservatorio Astronomico di Padova, Padova, Italy
Maxted, P.F.L.; Astrophysics Group, Keele University, Staffordshire, United Kingdom
Mordasini, C.; Center for Space and Habitability, University of Bern, Bern, Switzerland ; Physikalisches Institut, University of Bern, Bern, Switzerland
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, La Laguna, 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.; ETH Zurich, Department of Physics, Zurich, Switzerland ; Cavendish Laboratory, Cambridge, United Kingdom
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.; European Space Agency (ESA), European Space Research and Technology Centre (ESTEC), Noordwijk, Netherlands
Rauer, H.; Institute of Planetary Research, German Aerospace Center (DLR), Berlin, Germany ; Zentrum für Astronomie und Astrophysik, Technische Universität Berlin, Berlin, Germany ; Institut für Geologische Wissenschaften, Freie Universität Berlin, Berlin, Germany
Ribas, I.; Institut de Ciencies de l'Espai (ICE CSIC), Bellaterra, Spain ; Institut d'Estudis Espacials de Catalunya (IEEC), Barcelona, Spain
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
Sarajlic, M.; Physikalisches Institut, University of Bern, Bern, Switzerland
Scandariato, G.; INAF, Osservatorio Astrofisico di Catania, Catania, Italy
Ségransan, D.; Observatoire Astronomique de l'Université de Genève, Versoix, Switzerland
Sicilia, D.; INAF, Osservatorio Astrofisico di Catania, Catania, Italy
Simon, A.E.; Physikalisches Institut, University of Bern, Bern, Switzerland
Smith, A.M.S.; Institute of Planetary Research, German Aerospace Center (DLR), Berlin, Germany
Steller, M.; Space Research Institute, Austrian Academy of Sciences, Graz, Austria
Szabó, Gy M.; ELTE Eötvös Loránd University, Gothard Astrophysical Observatory, Szombathely, Hungary ; MTA-ELTE Exoplanet Research Group, Szombathely, Hungary
Thomas, N.; Physikalisches Institut, University of Bern, Bern, Switzerland
Udry, S.; Observatoire Astronomique de l'Université de Genève, Versoix, Switzerland
Ulmer, B.; Institute of Optical Sensor Systems, German Aerospace Center (DLR), Berlin, Germany
Van Grootel, Valérie ; Université de Liège - ULiège > Département d'astrophysique, géophysique et océanographie (AGO) > Astrophysique stellaire théorique et astérosismologie
Venturini, J.; Observatoire Astronomique de l'Université de Genève, Versoix, Switzerland
Walton, N.A.; Institute of Astronomy, University of Cambridge, Cambridge, United Kingdom
Wilson, T.G.; Centre for Exoplanet Science, SUPA School of Physics and Astronomy, University of St Andrews, St Andrews, United Kingdom
Wolter, D.; Institute of Planetary Research, German Aerospace Center (DLR), Berlin, Germany
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).We are grateful to the anonymous referee for the careful reading and thoughtful suggestions that improved this paper. He made the submission process an enjoyable experience. 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. EMV acknowledges support from the Centre for Space and Habitability (CSH). This work has been carried out within the framework of the National Centre of Competence in Research PlanetS supported by the Swiss National Science Foundation under grants 51NF40_182901 and 51NF40_205606. EMV acknowledges the financial support of the SNSF. EMV thanks Beatriz Campos Estrada for insightful discussion on the sublimation timescales of dust in disintegrating exoplanets. B.-O.D. acknowledges support from the Swiss State Secretariat for Education, Research and Innovation (SERI) under contract number MB22.00046. ABr was supported by the SNSA. S.G.S. acknowledges support from FCT through FCT contract no. CEECIND/00826/2018 and POPH/FSE (EC). This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (project SPICE DUNE, grant agreement no. 947634). LBo, VNa, IPa, GPi, RRa, GSc, VSi, and TZi acknowledge support from CHEOPS ASI-INAF agreement no. 2019-29-HH.0. DJB acknowledges financial support from the CSH, University of Bern. ML acknowledges support of the Swiss National Science Foundation under grant number PCEFP2_194576. ASt acknowledges support from the PLATO/CNES grant at CEA/IRFU/DAp and the French Programme National de Planétologie (PNP). This work was supported by FCT - Fundação para a Ciência 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 & POCI-01-0145-FEDER-032113, PTDC/FIS-AST/28953/2017 & POCI-01-0145-FEDER-028953, PTDC/FIS-AST/28987/2017 & 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. YAl acknowledges 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. ACC acknowledges support from STFC consolidated grant numbers ST/R000824/1 and ST/V000861/1, and UKSA grant number ST/R003203/1. This project was supported by the CNES. 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. L.D. is an F.R.S.-FNRS Postdoctoral Researcher. 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). DE acknowledges financial support from the Swiss National Science Foundation for project 200021_200726. M.F. and C.M.P. gratefully acknowledge the support of the Swedish National Space Agency (DNR 65/19, 174/18). DG gratefully acknowledges financial support from 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. MNG is the ESA CHEOPS Project Scientist and Mission Representative, and as such also responsible for the Guest Observers (GO) Programme. M.N.G. does not relay proprietary information between the GO and Guaranteed Time Observation (GTO) Programmes, and does not decide on the definition and target selection of the GTO Programme. S.H. gratefully acknowledges CNES funding through the grant 837319. 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 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. P.M. acknowledges support from STFC research grant number ST/M001040/1. This work was also partially supported by a grant from the Simons Foundation (PI Queloz, grant number 327127). IRI acknowledges support from the Spanish Ministry of Science and Innovation and the European Regional Development Fund through grant PGC2018-098153-B-C33, as well as the support of the Generalitat de Catalunya/CERCA programme. GyMSz acknowledges the support of the Hungarian National Research, Development and Innovation Office (NKFIH) grant K-125015, a PRODEX Experiment Agreement No. 4000137122, the Lendület LP2018-7/2021 grant of the Hungarian Academy of Science and the support of the city of Szombathely. V.V.G. is an F.R.S.-FNRS Research Associate. N.A.W. acknowledges UKSA grant ST/R004838/1. A.C.C. and T.W. acknowledge support from STFC consolidated grant numbers ST/R000824/1 and ST/V000861/1, and UKSA grant number ST/R003203/1. NCS acknowledges funding by the European Union (ERC, FIERCE, 101052347). Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or the European Research Council. Neither the European Union nor the granting authority can be held responsible for them. This research made use of exoplanet (Foreman-Mackey et al. 2021) and its dependencies (Agol et al. 2020; Kumar et al. 2019; Astropy Collaboration 2013, 2018; Kipping 2013; Luger et al. 2019; Salvatier et al. 2016; Theano Development Team 2016). We acknowledge the use of further software: batman (Kreidberg 2015), NumPy (Harris et al. 2020), matplotlib (Hunter 2007), corner (Foreman-Mackey 2016), astroquery (Ginsburg et al. 2019), seaborn (Waskom 2021) and scipy (Virtanen et al. 2020).
