Astrophysics - Earth and Planetary Astrophysics; Astrophysics - Solar and Stellar Astrophysics
Abstract :
[en] AU Mic is a young planetary system with a resolved debris disc showing signs of planet formation and two transiting warm Neptunes near mean-motion resonances. Here we analyse three transits of AU Mic b observed with the CHaracterising ExOPlanet Satellite (CHEOPS), supplemented with sector 1 and 27 Transiting Exoplanet Survey Satellite (TESS) photometry, and the All-Sky Automated Survey from the ground. The refined orbital period of AU Mic b is 8.462995 ± 0.000003 d, whereas the stellar rotational period is P[SUB]rot[/SUB] = 4.8367 ± 0.0006 d. The two periods indicate a 7:4 spin-orbit commensurability at a precision of 0.1%. Therefore, all transits are observed in front of one of the four possible stellar central longitudes. This is strongly supported by the observation that the same complex star-spot pattern is seen in the second and third CHEOPS visits that were separated by four orbits (and seven stellar rotations). Using a bootstrap analysis we find that flares and star spots reduce the accuracy of transit parameters by up to 10% in the planet-to-star radius ratio and the accuracy on transit time by 3-4 min. Nevertheless, occulted stellar spot features independently confirm the presence of transit timing variations (TTVs) with an amplitude of at least 4 min. We find that the outer companion, AU Mic c, may cause the observed TTVs.
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Szabó, Gy M.; 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
Gandolfi, D.; INAF, Osservatorio Astrofisico di Torino, via Osservatorio 20, 10025, Pino Torinese, Italy
Brandeker, A.; Department of Astronomy, Stockholm University, AlbaNova University Center, 10691, Stockholm, Sweden
Csizmadia, Sz; Institute of Planetary Research, German Aerospace Center (DLR), Rutherfordstrasse 2, 12489, Berlin, Germany
Garai, Z.; 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 ; Astronomical Institute, Slovak Academy of Sciences, 05960, Tatranská Lomnica, Slovakia
Billot, N.; Observatoire de Genève, Université de Genève, Chemin Pegasi, 51 1290, Versoix, Switzerland
Broeg, C.; Physikalisches Institut, University of Bern, Gesellsschaftstrasse 6, 3012, Bern, Switzerland
Ehrenreich, D.; Observatoire de Genève, Université de Genève, Chemin Pegasi, 51 1290, Versoix, Switzerland
Fortier, A.; Physikalisches Institut, University of Bern, Gesellsschaftstrasse 6, 3012, Bern, Switzerland
Fossati, L.; Space Research Institute, Austrian Academy of Sciences, Schmiedlstrasse 6, 8042, Graz, Austria
Hoyer, S.; Aix Marseille Univ, CNRS, CNES, LAM, Marseille, France
Kiss, L.; Konkoly Observatory, Research Centre for Astronomy and Earth Sciences, 1121, Budapest, Konkoly Thege Miklós út 15-17, Hungary ; ELTE Eötvös Loránd University, Institute of Physics, Pázmány Péter sétány 1/A, 1117, Budapest, Hungary ; Sydney Institute for Astronomy, School of Physics A29, University of Sydney, NSW, 2006, Australia
Lecavelier des Etangs, A.; Institut d'astrophysique de Paris, UMR7095 CNRS, Université Pierre & Marie Curie, 98bis blvd. Arago, 75014, Paris, France
Maxted, P. F. L.; Astrophysics Group, Keele University, Staffordshire, ST5 5BG, UK
Ribas, I.; Institut de Ciències de l'Espai (ICE, CSIC), Campus UAB, C/CanMagrans s/n, 08193, Bellaterra, Spain ; Institut d'Estudis Espacials de Catalunya (IEEC), Barcelona, Spain
Alibert, Y.; Physikalisches Institut, University of Bern, Gesellsschaftstrasse 6, 3012, Bern, Switzerland
Alonso, R.; Instituto de Astrofísica de Canarias (IAC), 38200, La Laguna, Tenerife, Spain ; Departamento de Astrofísica, Universidad de La Laguna (ULL), E-38206, La Laguna, Tenerife, Spain
Anglada Escudé, G.; Institut de Ciències de l'Espai (ICE, CSIC), Campus UAB, C/CanMagrans s/n, 08193, Bellaterra, Spain ; Institut d'Estudis Espacials de Catalunya (IEEC), Barcelona, Spain
Bárczy, T.; Admatis, Miskolc, Hungary
Barros, S. C. C.; Instituto de Astrofísica e Ciências do Espaço, Universidade do Porto, CAUP, Rua das Estrelas, 4150-762, Porto, Portugal ; Departamento de Física e Astronomia, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre, 4169-007, Porto, Portugal
Barrado, D.; Depto. de Astrofísica, Centro de Astrobiologia (CSIC-INTA), ESAC campus, 28692, Villanueva de la Cãda (Madrid), Spain
Baumjohann, W.; Space Research Institute, Austrian Academy of Sciences, Schmiedlstrasse 6, 8042, Graz, Austria
Beck, M.; Observatoire de Genève, Université de Genève, Chemin Pegasi, 51 1290, Versoix, Switzerland
Beck, T.; Center for Space and Habitability, Gesellsschaftstrasse 6, 3012, Bern, Switzerland
Bekkelien, A.; Observatoire de Genève, Université de Genève, Chemin Pegasi, 51 1290, Versoix, Switzerland
Bonfils, X.; Université Grenoble Alpes, CNRS, IPAG, 38000, Grenoble, France
Benz, W.; Physikalisches Institut, University of Bern, Gesellsschaftstrasse 6, 3012, Bern, Switzerland ; Center for Space and Habitability, Gesellsschaftstrasse 6, 3012, Bern, Switzerland
Busch, M.-D.; Physikalisches Institut, University of Bern, Gesellsschaftstrasse 6, 3012, Bern, Switzerland
Cabrera, J.; Institute of Planetary Research, German Aerospace Center (DLR), Rutherfordstrasse 2, 12489, Berlin, Germany
Charnoz, S.; Institut de Physique du Globe de Paris (IPGP), 1 rue Jussieu, 75005, Paris, France
Collier Cameron, A.; School of Physics and Astronomy, Physical Science Building, North Haugh, St Andrews, UK
Van Damme, C. Corral; ESTEC, European Space Agency, Keplerlaan 1, 2201, AZ Noordwijk, The Netherlands
Davies, M. B.; Lund Observatory, Dept. of Astronomy and Theoreical Physics, Lund University, Box 43, 22100, Lund, Sweden
Delrez, Laetitia ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Exotic
Deleuil, M.; Aix Marseille Univ, CNRS, CNES, LAM, Marseille, France
Demangeon, O. D. S.; Aix Marseille Univ, CNRS, CNES, LAM, Marseille, France ; Instituto de Astrofísica e Ciências do Espaço, Universidade do Porto, CAUP, Rua das Estrelas, 4150-762, Porto, Portugal
Demory, B.-O.; Center for Space and Habitability, Gesellsschaftstrasse 6, 3012, Bern, Switzerland
Erikson, A.; Institute of Planetary Research, German Aerospace Center (DLR), Rutherfordstrasse 2, 12489, Berlin, Germany
Fridlund, M.; Leiden Observatory, University of Leiden, PO Box 9513, 2300, RA Leiden, The Netherlands ; Department of Space, Earth and Environment, Chalmers University of Technology, Onsala Space Observatory, 43992, Onsala, Sweden
Futyan, D.; Observatoire de Genève, Université de Genève, Chemin Pegasi, 51 1290, Versoix, Switzerland
García Muñoz, A.; Center for Astronomy and Astrophysics, Technical University Berlin, Hardenberstrasse 36, 10623, Berlin, Germany
Gillon, Michaël ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Exotic
Guedel, M.; University of Vienna, Department of Astrophysics, Türkenschanzstrasse 17, 1180, Vienna, Austria
Guterman, P.; Aix Marseille Univ, CNRS, CNES, LAM, Marseille, France ; Division Technique INSU, BP 330, 83507, La Seyne cedex, France
Heng, K.; Center for Space and Habitability, Gesellsschaftstrasse 6, 3012, Bern, Switzerland ; Department of Physics, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL, UK
Isaak, K. G.; ESTEC, European Space Agency, Keplerlaan 1, 2201, AZ Noordwijk, The Netherlands
Lacedelli, G.; Dipartimento di Fisica e Astronomia "Galileo Galilei', Universià degli Studi di Padova, Vicolo dell'Osservatorio 3, 35122, Padova, Italy ; INAF, Osservatorio Astronomico di Padova, Vicolo dell'Osservatorio 5, 35122, Padova, Italy
Laskar, J.; IMCEE, UMR8028 CNRS, Observatoire de Paris, PSL Univ., Sorbonne Univ., 77 av. Denfert-Rochereau, 75014, Paris, France
Lendl, M.; Observatoire de Genève, Université de Genève, Chemin Pegasi, 51 1290, Versoix, Switzerland
Lovis, C.; Observatoire de Genève, Université de Genève, Chemin Pegasi, 51 1290, Versoix, Switzerland
Luntzer, A.; University of Vienna, Department of Astrophysics, Türkenschanzstrasse 17, 1180, Vienna, Austria
Olofsson, G.; Department of Astronomy, Stockholm University, AlbaNova University Center, 10691, Stockholm, Sweden
Osborn, H. P.; NCCR/PlanetS, Centre for Space & Habitability, University of Bern, Bern, Switzerland ; Department of Physics and Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
Ottensamer, R.; University of Vienna, Department of Astrophysics, Türkenschanzstrasse 17, 1180, Vienna, Austria
Pagano, I.; INAF, Osservatorio Astrofisico di Catania, Via S. Sofia 78, 95123, Catania, Italy
Pallé, E.; Instituto de Astrofísica de Canarias (IAC), 38200, La Laguna, Tenerife, Spain ; Departamento de Astrofísica, Universidad de La Laguna (ULL), E-38206, La Laguna, Tenerife, Spain
Peter, G.; Institute of Optical Sensor Systems, German Aerospace Center (DLR), Rutherfordstrasse 2, 12489, Berlin, Germany
Piazza, D.; Physikalisches Institut, University of Bern, Gesellsschaftstrasse 6, 3012, Bern, Switzerland
Piotto, G.; Dipartimento di Fisica e Astronomia "Galileo Galilei', Universià degli Studi di Padova, Vicolo dell'Osservatorio 3, 35122, Padova, Italy ; INAF, Osservatorio Astronomico di Padova, Vicolo dell'Osservatorio 5, 35122, Padova, Italy
Pollacco, D.; Department of Physics, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL, UK
Queloz, D.; Observatoire de Genève, Université de Genève, Chemin Pegasi, 51 1290, Versoix, Switzerland ; Astrophysics Group, Cavendish Laboratory, J.J. Thomson Avenue, Cambridge, CB3 0He, UK
Ragazzoni, R.; Dipartimento di Fisica e Astronomia "Galileo Galilei', Universià degli Studi di Padova, Vicolo dell'Osservatorio 3, 35122, Padova, Italy ; INAF, Osservatorio Astronomico di Padova, Vicolo dell'Osservatorio 5, 35122, Padova, Italy
Rando, N.; ESTEC, European Space Agency, Keplerlaan 1, 2201, AZ Noordwijk, The Netherlands
Rauer, H.; Institute of Planetary Research, German Aerospace Center (DLR), Rutherfordstrasse 2, 12489, Berlin, Germany ; Center for Astronomy and Astrophysics, Technical University Berlin, Hardenberstrasse 36, 10623, Berlin, Germany ; Institut für Geologische Wissenschaften, Freie Universität Berlin, 12249, Berlin, Germany
Santos, N. C.; Instituto de Astrofísica e Ciências do Espaço, Universidade do Porto, CAUP, Rua das Estrelas, 4150-762, Porto, Portugal ; Departamento de Física e Astronomia, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre, 4169-007, Porto, Portugal
Scandariato, G.; INAF, Osservatorio Astrofisico di Catania, Via S. Sofia 78, 95123, Catania, Italy
Ségransan, D.; Observatoire de Genève, Université de Genève, Chemin Pegasi, 51 1290, Versoix, Switzerland
Serrano, L. M.; Dipartimento di Fisica, Università degli Studi di Torino, Via Pietro Giuria 1, 10125, Torino, Italy
Sicilia, D.; INAF, Osservatorio Astrofisico di Catania, Via S. Sofia 78, 95123, Catania, Italy
Simon, Attila; Université de Berne
Smith, A. M. S.; Institute of Planetary Research, German Aerospace Center (DLR), Rutherfordstrasse 2, 12489, Berlin, Germany
Sousa, S. G.; Instituto de Astrofísica e Ciências do Espaço, Universidade do Porto, CAUP, Rua das Estrelas, 4150-762, Porto, Portugal
Steller, M.; Space Research Institute, Austrian Academy of Sciences, Schmiedlstrasse 6, 8042, Graz, Austria
Thomas, N.; Physikalisches Institut, University of Bern, Gesellsschaftstrasse 6, 3012, Bern, Switzerland
Udry, S.; Observatoire de Genève, Université de Genève, Chemin Pegasi, 51 1290, Versoix, Switzerland
Van Grootel, Valérie ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Astrophysique stellaire théorique et astérosismologie
Walton, N. A.; Astrophysics Group, Cavendish Laboratory, J.J. Thomson Avenue, Cambridge, CB3 0He, UK
Wilson, T. G.; School of Physics and Astronomy, Physical Science Building, North Haugh, St Andrews, UK)
