The changing face of AU Mic b: stellar spots, spin-orbit commensurability, and transit timing variations as seen by CHEOPS and TESS

Szabó, Gy. M. and Gandolfi, D. and Brandeker, A. and Csizmadia, Sz. and Garai, Z. and Billot, N. and Broeg, C. and Ehrenreich, D. and Fortier, A. and Fossati, L. and Hoyer, S. and Kiss, L. and Lecavelier des Etangs, A. and Maxted, P. F. L. and Ribas, I. and Alibert, Y. and Alonso, R. and Anglada Escudé, G. and Bàrczy, T. and Barros, S. C. C. and Barrado, D. and Baumjohann, W. and Beck, M. and Beck, T. and Bekkelien, A. and Bonfils, X. and Benz, W. and Borsato, L. and Busch, M. -D. and Cabrera Perez, Juan and Charnoz, S. and Collier Cameron, A. and Van Damme, C. Corral and Davies, M. B. and Delrez, L. and Deleuil, M. and Demangeon, O. D. S. and Demory, B. -O. and Erikson, A and Fridlund, M. and Futyan, D. and Garcia Munoz, A. and Gillon, M. and Guedel, M. and Guterman, P. and Heng, K. and Isaak, K. G. and Lacedelli, G. and Laskar, J. and Lendl, M. and Lovis, C. and Luntzer, A. and Magrin, D. and Nascimbeni, V. and Olofsson, G. and Osborn, H. P. and Ottensamer, R. and Pagano, I. and Palle, E. and Peter, G. and Piazza, D. and Piotto, G. and Pollacco, D. and Queloz, D. and Ragazzoni, R. and Rando, N. and Rauer, H. and Santos, N. C. and Scandariato, G. and Segransan, D. and Serrano, L. M. and Sicilia, D. and Simon, A. E. and Smith, Alexis M S and Sousa, S. G. and Steller, M. and Thomas, N. and Udry, S. and Van Grootel, V. and Walton, N. A. and Wilson, T. G. (2021) The changing face of AU Mic b: stellar spots, spin-orbit commensurability, and transit timing variations as seen by CHEOPS and TESS. Astronomy & Astrophysics, 654, A159. EDP Sciences. doi: 10.1051/0004-6361/202140345. ISSN 0004-6361.

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Official URL: https://www.aanda.org/articles/aa/abs/2021/10/aa40345-21/aa40345-21.html

Abstract

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 Prot = 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.

Item URL in elib:

https://elib.dlr.de/145445/

Document Type:

Article

Title:

The changing face of AU Mic b: stellar spots, spin-orbit commensurability, and transit timing variations as seen by CHEOPS and TESS

Authors:

Authors	Institution or Email of Authors	Author's ORCID iD
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	UNSPECIFIED
Gandolfi, D.	Dipartimento di Fisica, Universitá di Torino, Via P. Giuria 1, I-10125, Torino, Italy	UNSPECIFIED
Brandeker, A.	Department of Astronomy , Stockholm University, SE-106 91 Stockholm, Sweden	UNSPECIFIED
Csizmadia, Sz.	szilard.csizmadia (at) dlr.de	https://orcid.org/0000-0001-6803-9698
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, 0596	https://orcid.org/0000-0001-9483-2016
Billot, N.	Observatoire de Genève, University of Geneva, Switzerland	UNSPECIFIED
Broeg, C.	Physikalisches Institut, University of Bern, Bern, Switzerland	UNSPECIFIED
Ehrenreich, D.	Observatoire de Genève, University of Geneva, Switzerland	UNSPECIFIED
Fortier, A.	Physikalisches Institut, University of Bern, Bern, Switzerland	UNSPECIFIED
Fossati, L.	Space Research Institute, Austrian Academy of Sciences, Schmiedlstrasse 6, 8041 Graz, Austria	UNSPECIFIED
Hoyer, S.	Laboratoire d’Astrophysique de Marseille, Univ. de Provence, France	UNSPECIFIED
Kiss, L.	Konkoly Observatory, Research Centre for Astronomy and Earth, Budapest, Hungary	UNSPECIFIED
Lecavelier des Etangs, A.	Institut d Astrophysique de Paris, CNRS, UMR 7095 & Sorbonne Universites, UPMC Paris 6, 98 bis bd Arago, 75014 Paris, France	UNSPECIFIED
Maxted, P. F. L.	Astrophysics Group, Keele University, Staffordshire ST5 5BG, UK	UNSPECIFIED
Ribas, I.	Institute d´Estudis Espacials de Catalunya and Instituto de Ciencias des Espacio, Barcelona, Spain	UNSPECIFIED
Alibert, Y.	Physikalisches Institut, University of Bern;Observatoire de Besançon, Institut UTINAM, France	UNSPECIFIED
Alonso, R.	Instituto de Astrofisica de Canarias, C/via Lactea s/n, 38205 La Laguna, Tenerife, Spain	UNSPECIFIED
Anglada Escudé, G.	Institut de Ciències de l’Espai (ICE, CSIC), Campus UAB, CanMagrans s/n, 08193 Bellaterra, Spain; Institut d’Estudis Espacials de Catalunya (IEEC), 08034 Barcelona,Spain	UNSPECIFIED
Bàrczy, T.	Admatis, Miskolc, Hungary	UNSPECIFIED
Barros, S. C. C.	Instituto de Astrofisica e Ciencias do Espaco, Universidade do Porto, CAUP, Rua das Estrelas, 4150-762 Porto, Portugal	UNSPECIFIED
Barrado, D.	Departamento de Astrofisica, Centro de Astrobiologia (INTA-CSIC), Campus ESAC (ESA)Camino Bajo del Castillo s/n 28692 Villanueva de la Canada, Spain	UNSPECIFIED
Baumjohann, W.	Space Research Institute, Austrian Academy of Sciences, Graz, Austria	https://orcid.org/0000-0001-6271-0110
Beck, M.	Observatoire de Genève, University of Geneva, Switzerland	UNSPECIFIED
Beck, T.	Center for Space and Habitability, University of Bern, Gesellschaftsstraße 6, 3012, Bern, Switzerland	UNSPECIFIED
Bekkelien, A.	Observatoire Astronomique de l'Université de Genève, Chemin Pegasi 51, 1290 Versoix, Switzerland	UNSPECIFIED
Bonfils, X.	Institut de Planétologie et d'Astrophysique, University of Grenoble, France	UNSPECIFIED
Benz, W.	Physikalisches Institut,University of Bern, Sidlerstraße 5, CH-3012 Bern, Switzerland	UNSPECIFIED
Borsato, L.	Dipartimento di Fisica e Astronomia, Universita degli Studi di Padova, via Marzolo 8, 35131 Padova, Italy	https://orcid.org/0000-0001-8627-9628
Busch, M. -D.	Physikalisches Institut, University of Bern, Gesellsschaftstrasse 6, 3012, Bern, Switzerland	UNSPECIFIED
Cabrera Perez, Juan	Juan.Cabrera (at) dlr.de	https://orcid.org/0000-0001-6653-5487
Charnoz, S.	Institut de Physique du Globe, Paris, France	UNSPECIFIED
Collier Cameron, A.	SUPA, School of Physics and Astronomy, University of St. Andrews, North Haugh, Fife KY16 9SS, UK	UNSPECIFIED
Van Damme, C. Corral	ESTEC, European Space Agency, Keplerlaan 1, 2201, AZ Noordwijk, The Netherlands	UNSPECIFIED
Davies, M. B.	Lund Observatory, Department of Astronomy and Theoretical Physics, Lund University, 22100, Lund, Sweden	UNSPECIFIED
Delrez, L.	Institut d’Astrophysique et de Geophysique, Universite de Liege, Belgium	UNSPECIFIED
Deleuil, M.	Aix Marseille Universite, CNRS, LAM (Laboratoire d Astrophysique de Marseille) UMR 7326, 13388, Marseille, France	UNSPECIFIED
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	UNSPECIFIED
Demory, B. -O.	Center for Space and Habitability, Gesellsschaftstrasse 6, 3012, Bern, Switzerland	UNSPECIFIED
Erikson, A	anders.erikson (at) dlr.de	UNSPECIFIED
Fridlund, M.	Department of Space, Earth and Environment, Chalmers University of Technology, Onsala Space Observatory, 439 92, Onsala, Sweden; Leiden Observatory, Leiden University, 2333CA, Leiden, The Netherlands	UNSPECIFIED
Futyan, D.	Observatoire de Genève, University of Geneva, Switzerland	UNSPECIFIED
Garcia Munoz, A.	Zentrum fuer Astronomie und Astrophysik, Technische Universitaet Berlin, Germany	https://orcid.org/0000-0003-1756-4825
Gillon, M.	Institut d'Astrophysique et de Géophysique, Universitée de Liège, Allée du 6 août 17, B-4000 Liège, Belgium	UNSPECIFIED
Guedel, M.	University of Vienna, Department of Astrophysics, Türkenschanzstrasse 17, 1180, Vienna, Austria	UNSPECIFIED
Guterman, P.	Laboratoire d'Astrophysique de Marseille, France	UNSPECIFIED
Heng, K.	Center for Space and Habitability, University of Bern, Gesellschaftsstraße 6, 3012, Bern, Switzerland	UNSPECIFIED
Isaak, K. G.	ESA/ESTEC, Noordwijk, Niederlande	UNSPECIFIED
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	UNSPECIFIED
Laskar, J.	IMCCE, UMR8028 CNRS, Observatoire de Paris, PSL Univ.,Sorbonne Univ., 77 av. Denfert-Rochereau, 75014 Paris, France	UNSPECIFIED
Lendl, M.	Geneva Observatory, University of Geneva, Chemin des Mailettes 51, 1290, Versoix, Switzerland	UNSPECIFIED
Lovis, C.	Geneva Observatory, University of Geneva, Chemin des Mailettes 51, 1290, Versoix, Switzerland	UNSPECIFIED
Luntzer, A.	Department of Astrophysics, University of Vienna	UNSPECIFIED
Magrin, D.	INAF, Astronomical Institute, Padua, Italy	UNSPECIFIED
Nascimbeni, V.	NAF - Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, Padova, IT-35122, Italy	UNSPECIFIED
Olofsson, G.	Department of Astronomy, Stockholm University, AlbaNova University Center, 10691 Stockholm, Sweden	UNSPECIFIED
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	UNSPECIFIED
Ottensamer, R.	Dept. of Astrophysics, University of Vienna, Austria	UNSPECIFIED
Pagano, I.	INAF - Osservatorio Astrofisico di Catania, Via S. Sofia 78, 95123 Catania, Italy	UNSPECIFIED
Palle, E.	Instituto de Astrofisica de Canarias (IAC), 38205, La Laguna, Tenerife, Spain; Departamento de Astrofisica, Universidad de La Laguna, 38206, La Laguna, Tenerife, Spain	UNSPECIFIED
Peter, G.	Gisbert.Peter (at) dlr.de	UNSPECIFIED
Piazza, D.	Physics Institute, Space Research & Planetary Sciences, University of Bern, Sidlerstr. 5, CH-3012 Bern, Switzerland	UNSPECIFIED
Piotto, G.	INAF – Osservatorio Astronomico di Padova, vicolo dell Osservatorio 5, 35122 Padova, Italy	UNSPECIFIED
Pollacco, D.	Department of Physics, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL, UK; Centre for Exoplanets and Habitability, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL, UK	UNSPECIFIED
Queloz, D.	Cavendish Laboratory, J J Thomson Avenue, Cambridge, CB3 0HE, UK	UNSPECIFIED
Ragazzoni, R.	Dipartimento di Fisica e Astronomia, Universita degli Studi di Padova, Vicolo dell Osservatorio 3, 35122 Padova, Italy	UNSPECIFIED
Rando, N.	ESA/ESTEC, Noordwijk, Niederlande	UNSPECIFIED
Rauer, H.	Heike.Rauer (at) dlr.de	UNSPECIFIED
Santos, N. C.	Instituto de Astrofisica e Ciencias do Espaco, Universidade do Porto, CAUP, Rua das Estrelas, 4150-762 Porto, Portugal; Departamento de Fisica e Astronomia, Faculdade de Ciencias, Universidade do Porto, Rua Campo Alegre, 4169-007 Porto, Portugal	UNSPECIFIED
Scandariato, G.	NAF – Osservatorio Astronomico di Palermo, Piazza del Parlamento 1, 90134 Palermo, Italy	UNSPECIFIED
Segransan, D.	Observatoire de Geneve, Universite de Geneve, 51 Chemin des Maillettes, 1290 Sauverny, Switzerland	UNSPECIFIED
Serrano, L. M.	instituto de astrofísica e ciências do espaço, universidade do porto, caup, rua das estrelas, 4150-762 porto, portugal	UNSPECIFIED
Sicilia, D.	INAF - Osservatorio Astrofisico di Catania, Via S. Sofia 78, 95123 Catania, Italy	UNSPECIFIED
Simon, A. E.	Center for Space and Habitability, University of Bern, Switzerland	UNSPECIFIED
Smith, Alexis M S	Alexis.Smith (at) dlr.de	https://orcid.org/0000-0002-2386-4341
Sousa, S. G.	Instituto de Astrofisica e Ciencias do Espaco, Universidade do Porto, CAUP, Rua das Estrelas, 4150-762 Porto, Portugal	UNSPECIFIED
Steller, M.	Space Research Institute, Austrian Academy of Sciences, Schmiedlstrasse 6, 8042, Graz, Austria	UNSPECIFIED
Thomas, N.	Physikalisches Institut, Uni Bern Siedlerstrasse, Bern, 3012 Switzerland	UNSPECIFIED
Udry, S.	Observatoire de Genève, Sauverny, Switzerland	UNSPECIFIED
Van Grootel, V.	Université de Liege, Belgium	UNSPECIFIED
Walton, N. A.	Institute of Astronomy, University of Cambridge, Cambridge, UK	UNSPECIFIED
Wilson, T. G.	School of Physics and Astronomy, St. Andrews, UK	https://orcid.org/0000-0001-8749-1962

Date:

2021

Journal or Publication Title:

Astronomy & Astrophysics

Refereed publication:

Yes

Open Access:

Yes

Gold Open Access:

In SCOPUS:

Yes

In ISI Web of Science:

Yes

Volume:

654

DOI :

10.1051/0004-6361/202140345

Page Range:

A159

Publisher:

EDP Sciences

ISSN:

0004-6361

Status:

Published

Keywords:

Astrophysics - Earth and Planetary Astrophysics, Astrophysics - Solar and Stellar Astrophysics

HGF - Research field:

Aeronautics, Space and Transport

HGF - Program:

Space

HGF - Program Themes:

Space Exploration

DLR - Research area:

Raumfahrt

DLR - Program:

R EW - Space Exploration

DLR - Research theme (Project):

R - CHEOPS Science, R - Project CHEOPS

Location:

Berlin-Adlershof

Institutes and Institutions:

Institute of Planetary Research > Extrasolar Planets and Atmospheres
Institute of Planetary Research > Leitungsbereich PF
Institute of Optical Sensor Systems > Space Instruments

Deposited By:

Smith, Dr Alexis M S

Deposited On:

10 Nov 2021 11:23

Last Modified:

10 Nov 2021 11:23

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