Planetary systems; Planets and satellites: detection; Planets and satellites: fundamental parameters; Planets and satellites: individual: HD 108236; Planets and satellites: individual: TOI 1233; Host-stars; Planet and satellite: individual: HD 108236; Planet and satellite: individual: TOI 1233; Planetary system; Planets and satellites: detections; Planets and satellites: individual; Timing variations; Transit timing; Astronomy and Astrophysics; Space and Planetary Science; astro-ph.EP
Abstract :
[en] Context. The HD 108236 system was first announced with the detection of four small planets based on TESS data. Shortly after, the transit of an additional planet with a period of 29.54 d was serendipitously detected by CHEOPS. In this way, HD 108236 (V = 9.2) became one of the brightest stars known to host five small transiting planets (Rp < 3 Ro˙). Aims. We characterize the planetary system by using all the data available from CHEOPS and TESS space missions. We use the flexible pointing capabilities of CHEOPS to follow up the transits of all the planets in the system, including the fifth transiting body. Methods. After updating the host star parameters by using the results from Gaia eDR3, we analyzed 16 and 43 transits observed by CHEOPS and TESS, respectively, to derive the planets' physical and orbital parameters. We carried out a timing analysis of the transits of each of the planets of HD 108236 to search for the presence of transit timing variations. Results. We derived improved values for the radius and mass of the host star (R∗ = 0.876 ± 0.007 R0 and M∗ = 0.867-0.046+0.047M). We confirm the presence of the fifth transiting planet f in a 29.54 d orbit. Thus, the HD 108236 system consists of five planets of Rb = 1.587±0.028, Rc = 2.122±0.025, Rd = 2.629 ± 0.031, Re = 3.008 ± 0.032, and Rf = 1.89 ± 0.04 [Ro˙]. We refine the transit ephemeris for each planet and find no significant transit timing variations for planets c, d, and e. For planets b and f, instead, we measure significant deviations on their transit times (up to 22 and 28 min, respectively) with a non-negligible dispersion of 9.6 and 12.6 min in their time residuals. Conclusions. We confirm the presence of planet f and find no significant evidence for a potential transiting planet in a 10.9 d orbital period, as previously suggested. Further monitoring of the transits, particularly for planets b and f, would confirm the presence of the observed transit time variations. HD 108236 thus becomes a key multi-planetary system for the study of formation and evolution processes. The reported precise results on the planetary radii - together with a profuse RV monitoring - will allow for an accurate characterization of the internal structure of these planets.
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Hoyer, S. ; Aix-Marseille Univ., Cnrs, Cnes, Lam, Marseille, France
Bonfanti, A. ; Space Research Institute, Austrian Academy of Sciences, Graz, Austria
Leleu, A.; Observatoire Astronomique de l' Université de Genève, Versoix, Switzerland ; Physikalisches Institut, University of Bern, Bern, Switzerland
Acuña, L. ; Aix-Marseille Univ., Cnrs, Cnes, Lam, Marseille, France
Serrano, L.M. ; Dipartimento di Fisica, Universita Degli Studi di Torino, Torino, Italy
Deleuil, M.; Aix-Marseille Univ., Cnrs, Cnes, Lam, Marseille, France
Bekkelien, A. ; Observatoire Astronomique de l' Université de Genève, Versoix, Switzerland
Broeg, C.; Physikalisches Institut, University of Bern, Bern, Switzerland ; Center for Space and Habitability, Bern, Switzerland
Florén, H.-G. ; Department of Astronomy, Stockholm University, AlbaNova University Center, Stockholm, Sweden ; Department of Astronomy, Stockholm University, Stockholm, Sweden
Queloz, D. ; Eth Zurich, Department of Physics, Zurich, Switzerland ; Cavendish Laboratory, Cambridge, United Kingdom
Wilson, T.G. ; Centre for Exoplanet Science, Supa School of Physics and Astronomy, University of St Andrews, St Andrews, United Kingdom
Sousa, S.G. ; Instituto de Astrofisica e Ciencias Do Espaco, Universidade Do Porto, Caup, Porto, Portugal
Hooton, M.J. ; Physikalisches Institut, University of Bern, Bern, Switzerland ; Cavendish Laboratory, Cambridge, United Kingdom
Adibekyan, V. ; Instituto de Astrofisica e Ciencias Do Espaco, Universidade Do Porto, Caup, 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), Campus Uab, Bellaterra, Spain ; Institut d' Estudis Espacials de Catalunya (IEEC), Barcelona, Spain
Asquier, J.; Estec, European Space Agency, Noordwijk, Netherlands
Bárczy, T.; Admatis, Miskolc, Hungary
Barrado, 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
Benz, W.; Physikalisches Institut, University of Bern, Bern, Switzerland ; Center for Space and Habitability, Bern, Switzerland
Billot, N.; Observatoire Astronomique de l' Université de Genève, Versoix, Switzerland
Biondi, F.; Max Planck Institute for Extraterrestrial Physics, Garching bei München, Germany ; Inaf, Osservatorio Astronomico di Padova, Padova, Italy
Bonfils, X.; Université Grenoble Alpes, Cnrs, Ipag, Grenoble, France
Brandeker, A. ; Department of Astronomy, Stockholm University, AlbaNova University Center, Stockholm, Sweden
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
Davies, M.B.; Centre for Mathematical Sciences, Lund University, Lund, Sweden
Delrez, Laetitia ; Université de Liège - ULiège > Département d'astrophysique, géophysique et océanographie (AGO) > Exoplanets in Transit: Identification and Characterization
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
Demory, B.-O. ; Center for Space and Habitability, Bern, Switzerland
Ehrenreich, D. ; Observatoire Astronomique de l' Université de Genève, Versoix, Switzerland
Erikson, A.; Institute of Planetary Research, German Aerospace Center (DLR), Berlin, Germany
Fortier, A. ; Physikalisches Institut, University of Bern, Bern, Switzerland ; Center for Space and Habitability, Bern, Switzerland
Fossati, L.; Space Research Institute, Austrian Academy of Sciences, Graz, Austria
Fridlund, M.; Leiden Observatory, University of Leiden, RA 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
Gillon, Michaël ; Université de Liège - ULiège > Département d'astrophysique, géophysique et océanographie (AGO)
Güdel, M. ; University of Vienna, Department of Astrophysics, Vienna, Austria
Hara, N.; Observatoire Astronomique de l' Université de Genève, Versoix, Switzerland
Heng, K. ; Center for Space and Habitability, Bern, Switzerland ; Department of Physics, University of Warwick, Coventry, United Kingdom
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
Jenkins, J.M. ; Nasa Ames Research Center, Moffett Field, United States
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
Latham, D.W. ; Center for Astrophysics, Harvard & Smithsonian, Cambridge, United States
Lecavelier Des Etangs, A. ; Institut d' Astrophysique de Paris, Cnrs, Umr 7095, Sorbonne Université, Paris, France
Lendl, M. ; Observatoire Astronomique de l' Université de Genève, Versoix, Switzerland
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
Maxted, P.F.L. ; Astrophysics Group, Keele University, Staffordshire, United Kingdom
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
Persson, C.M. ; Department of Space Earth and Environment, Chalmers University of Technology, Onsala Space Observatory, Onsala, Sweden
Peter, G.; Institute of Optical Sensor Systems, German Aerospace Center (DLR), Berlin, Germany
Piazza, D.; Physikalisches Institut, University of Bern, Bern, Switzerland
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
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 ; 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), Campus Uab, Bellaterra, Spain ; Institut d' Estudis Espacials de Catalunya (IEEC), Barcelona, Spain
Ricker, G.R.; Department of Physics, Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, United States
Salmon, S.; Observatoire Astronomique de l' Université de Genève, Versoix, 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
Scandariato, G. ; Inaf, Osservatorio Astrofisico di Catania, Catania, Italy
Seager, S.; Department of Physics, Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, United States ; Department of Earth Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, United States ; Department of Aeronautics and Astronautics, Mit, Cambridge, United States
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
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
Twicken, J.D. ; Nasa Ames Research Center, Moffett Field, United States ; Seti Institute, Mountain View, United States
Udry, S.; Observatoire Astronomique de l' Université de Genève, Versoix, Switzerland
Van Grootel, Valérie ; Université de Liège - ULiège > Département d'astrophysique, géophysique et océanographie (AGO) > Astrophysique stellaire théorique et astérosismologie
Vanderspek, R.K.; Department of Physics, Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, United States
Walton, N.A. ; Institute of Astronomy, University of Cambridge, Cambridge, United Kingdom
Westerdorff, K.; Institute of Optical Sensor Systems, German Aerospace Center (DLR), Berlin, Germany
Winn, J.N. ; Department of Astrophysical Sciences, Princeton University, Princeton, United States
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. Funding for the TESS mission is provided by NASA’s Science Mission Directorate. We acknowledge the use of public TESS data from pipelines at the TESS Science Office and at the TESS Science Processing Operations Center. Resources supporting this work were provided by the NASA High-End Computing (HEC) Program through the NASA Advanced Supercomputing (NAS) Division at Ames Research Center for the production of the SPOC data products. This paper includes data collected by the TESS mission that are publicly available from the Mikulski Archive for Space Telescopes (MAST). SH gratefully acknowledges CNES funding through the grant 837319. The authors acknowledge support from the Swiss NCCR PlanetS and the Swiss National Science Foundation. LMS gratefully acknowledges financial support from the CRT foundation under Grant No. 2018.2323 ‘Gaseous or rocky? Unveiling the nature of small worlds’. This project was supported by the CNES. This work was also partially supported by a grant from the Simons Foundation (PI Queloz, grant number 327127). ACC and TW acknowledge support from STFC consolidated grant numbers ST/R000824/1 and ST/V000861/1, and UKSA grant number ST/R003203/1. S.G.S. acknowledges support from FCT through FCT contract nr. CEECIND/00826/2018 and POPH/FSE (EC). YA and MJH 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. XB, SC, DG, MF and JL acknowledge their role as ESA-appointed CHEOPS science team members. ABr was supported by the SNSA. ACC acknowledges support from STFC consolidated grant numbers ST/R000824/1 and ST/V000861/1, and UKSA grant number ST/R003203/1. 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 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. B.-O.D. acknowledges support from the Swiss National Science Foundation (PP00P2-190080). 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. and C.M.P. gratefully acknowledge the support of the Swedish National Space Agency (DNR 65/19, 174/18). D.G. gratefully acknowledges financial support from the CRT foundation under Grant No. 2018.2323 “Gaseousor rocky? Unveiling the nature of small worlds”. M.G. is an F.R.S.-FNRS Senior Research Associate. 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 Rgion Île-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. M.L. acknowledges support of the Swiss National Science Foundation under grant number PCEFP2_194576. P.M. acknowledges support from STFC research grant number ST/M001040/1. G.Sc., G.Pi., I.Pa., L.Bo., V.Na. and R.Ra. acknowledge the funding support from Italian Space Agency (ASI) regulated by “Accordo ASI-INAF n. 2013-016-R.0 del 9 luglio 2013 e integrazione del 9 luglio 2015 CHEOPS Fasi A/B/C”. I.R.I. 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. S.S. has received funding from the EuropeanResearch Council (ERC) under the European Union’s Horizon 2020 researchand innovation program (grant agreement No 833925, project STAREX). Gy.M.Sz. acknowledges the support of the Hungarian National Research, Development and Innovation Office (NKFIH) grant K-125015, a PRODEX Institute Agreement between the ELTE Eötvös Loránd University and the European Space Agency (ESA-D/SCI-LE-2021-0025), 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. This research has made use of computing facilities operated by CeSAM data center at LAM, Marseille, France. We also thank J.C. 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