Transit-timing variations in the AU Mic system observed with CHEOPS

arXiv (Cornell University)

Abstract

AU Mic is a very active M dwarf with an edge-on debris disk and two transiting sub-Neptunes with a possible third planetary companion. The two transiting planets exhibit significant transit-timing variations (TTVs) that are caused by the gravitational interaction between the bodies in the system. Using photometrical observations taken with the CHaracterizing ExOPlanet Satellite (CHEOPS), our goal is to constrain the planetary radii, the orbital distances and periods of AU Mic b and c. We aim to determine the superperiod of the TTVs for AU Mic b and to update the transit ephemeris for both planets. Based on the observed TTVs, we study the possible presence of a third planet in the system. We conducted high precision photometric observations with CHEOPS in 2022 and 2023. We used Allesfitter to fit the planetary transits and to constrain the planetary and orbital parameters. We combined our new measurements with results from previous years to determine the periods and amplitudes of the TTVs. We applied dynamical modelling based on TTV measurements from the 2018-2023 period to reconstruct the perceived variations. The orbital distances and periods for AU Mic b and c agree with the results from previous works. However, the values for the planetary radii deviate slightly from previous values, which we attribute to the effect of stellar spots. AU Mic c showed very strong TTVs, with transits that occurred ~80 minutes later in 2023 than in 2021. Through dynamical analysis of the system, we found that the observed TTVs can be explained by a third planet with an orbital period of ~12.6 days and a mass of 0.203+0.022-0.024 M_E. We explored the orbital geometry of the system and found that AU Mic c has a misaligned retrograde orbit. Due limited number of observations the exact configuration and planetary parameters could not be determined. Further monitoring with CHEOPS may improve these results.

Authors 88

1. Ádám Boldog
2. Gy. M. Szabó
3. L. Kriskovics
4. L. Borsato

   Osservatorio Astronomico di Padova · National Institute for Astrophysics

   Affiliation as printed

   INAF , Osservatorio Astronomico di Padova , Vicolo dell'Osservatorio 5 , 35122 Padova , Italy

5. D. Gandolfi

   University of Turin

   Affiliation as printed

   Dipartimento di Fisica , Università degli Studi di Torino , via Pietro Giuria 1 , I-10125 , Torino , Italy

6. M. Lendl

   University of Geneva

   Affiliation as printed

   Observatoire astronomique de l'Université de Genève , Chemin Pe- gasi 51 , 1290 Versoix , Switzerland

7. Maximilian N. Günther
8. A. Heitzmann

   University of Geneva

   Affiliation as printed

   Observatoire astronomique de l'Université de Genève , Chemin Pe- gasi 51 , 1290 Versoix , Switzerland

9. T. G. Wilson

   University of Warwick

   Affiliation as printed

   Department of Physics , University of Warwick , Gibbet Hill Road , Coventry CV4 7AL , United Kingdom

10. A. Brandeker

    Stockholm University · AlbaNova

    Affiliation as printed

    Department of Astronomy , Stockholm University , AlbaNova Uni- versity Center , 10691 Stockholm , Sweden

11. Z. Garai

    Slovak Academy of Sciences · Astronomical Institute of the Slovak Academy of Sciences

    Affiliation as printed

    Astronomical Institute , Slovak Academy of Sciences , 05960 Tatran- ská Lomnica , Slovakia

12. Yann Alibert

    University of Bern · Center for Space and Habitability

    Affiliation as printed

    Center for Space and Habitability , University of Bern , Gesellschaftsstrasse 6 , 3012 Bern , Switzerland

    Space Research and Planetary Sciences , Physics Institute , Univer- sity of Bern , Gesellschaftsstrasse 6 , 3012 Bern , Switzerland

13. R. Alonso

    Universidad de La Laguna · Instituto de Astrofísica de Canarias

    Affiliation as printed

    Departamento de Astrofísica , Universidad de La Laguna , As- trofísico Francisco Sanchez s/n , 38206 La Laguna , Tenerife , Spain

    Instituto de Astrofísica de Canarias , Vía Láctea s/n , 38200 La La- guna , Tenerife , Spain

14. T. Bárczy
15. D. Barrado

    Centro de Astrobiología

    Affiliation as printed

    Depto. de Astrofísica , Centro de Astrobiología (CSIC-INTA) , ESAC campus , 28692 Villanueva de la Cañada (Madrid) , Spain

16. S. C. C. Barros

    Universidade do Porto · Institute of Astrophysics and Space Sciences · Centro de Astrofísica da Universidade do Porto

    Affiliation as printed

    Departamento de Fisica e Astronomia , Faculdade de Ciencias , Uni- versidade do Porto , Rua do Campo Alegre , 4169-007 Porto , Portugal

    Instituto de Astrofisica e Ciencias do Espaco , Universidade do Porto , CAUP , Rua das Estrelas , 4150-762 Porto , Portugal

17. W. Baumjohann

    Austrian Academy of Sciences · Space Research Institute

    Affiliation as printed

    Space Research Institute , Austrian Academy of Sciences , Schmiedlstrasse 6 , A-8042 Graz , Austria

18. W. Benz

    University of Bern · Center for Space and Habitability

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    Center for Space and Habitability , University of Bern , Gesellschaftsstrasse 6 , 3012 Bern , Switzerland

    Space Research and Planetary Sciences , Physics Institute , Univer- sity of Bern , Gesellschaftsstrasse 6 , 3012 Bern , Switzerland

19. N. Billot

    University of Geneva

    Affiliation as printed

    Observatoire astronomique de l'Université de Genève , Chemin Pe- gasi 51 , 1290 Versoix , Switzerland

20. Christopher H. Broeg

    University of Bern · Center for Space and Habitability

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    Center for Space and Habitability , University of Bern , Gesellschaftsstrasse 6 , 3012 Bern , Switzerland

    Space Research and Planetary Sciences , Physics Institute , Univer- sity of Bern , Gesellschaftsstrasse 6 , 3012 Bern , Switzerland

21. Andrew Collier Cameron

    University of St Andrews

    Affiliation as printed

    Centre for Exoplanet Science , SUPA School of Physics and Astron- omy , University of St Andrews , North Haugh , St Andrews KY16 9SS , UK

22. Alexandre C. M. Correia

    Centro de Física da Universidade de Coimbra · University of Coimbra

    Affiliation as printed

    CFisUC , Departamento de Física , Universidade de Coimbra , 3004- 516 Coimbra , Portugal

23. Sz. Csizmadia
24. Patricio E. Cubillos

    Austrian Academy of Sciences · Space Research Institute · Osservatorio Astrofisico di Torino

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    INAF , Osservatorio Astrofisico di Torino , Via Osservatorio, 20 , I- 10025 Pino Torinese To , Italy

    Space Research Institute , Austrian Academy of Sciences , Schmiedlstrasse 6 , A-8042 Graz , Austria

25. M. B. Davies

    Lund University

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    Centre for Mathematical Sciences , Lund University , Box 118 , 221 00 Lund , Sweden

26. M. Deleuil

    Centre National de la Recherche Scientifique · Aix-Marseille Université · Laboratoire d’Astrophysique de Marseille

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    Aix Marseille Univ , CNRS , CNES , LAM , 38 rue Frédéric Joliot- Curie , 13388 Marseille , France

27. A. Deline

    University of Geneva

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    Observatoire astronomique de l'Université de Genève , Chemin Pe- gasi 51 , 1290 Versoix , Switzerland

28. Olivier D S Demangeon

    Universidade do Porto · Institute of Astrophysics and Space Sciences · Centro de Astrofísica da Universidade do Porto

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    Departamento de Fisica e Astronomia , Faculdade de Ciencias , Uni- versidade do Porto , Rua do Campo Alegre , 4169-007 Porto , Portugal

    Instituto de Astrofisica e Ciencias do Espaco , Universidade do Porto , CAUP , Rua das Estrelas , 4150-762 Porto , Portugal

29. B. -O. Demory

    University of Bern · Center for Space and Habitability

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    Center for Space and Habitability , University of Bern , Gesellschaftsstrasse 6 , 3012 Bern , Switzerland

    Space Research and Planetary Sciences , Physics Institute , Univer- sity of Bern , Gesellschaftsstrasse 6 , 3012 Bern , Switzerland

30. A. Derekas
31. B. Edwards Aachen SRON Netherlands Institute for Space Research

    Space Research Organisation Netherlands

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    SRON Netherlands Institute for Space Research , Niels Bohrweg 4 , 2333 CA Leiden , Netherlands

32. J. A. Egger

    University of Bern

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    Space Research and Planetary Sciences , Physics Institute , Univer- sity of Bern , Gesellschaftsstrasse 6 , 3012 Bern , Switzerland

33. David Ehrenreich

    University of Geneva

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    Centre Vie dans l'Univers , Faculté des sciences , Université de Genève , Quai Ernest-Ansermet 30 , 1211 Genève 4 , Switzerland

    Observatoire astronomique de l'Université de Genève , Chemin Pe- gasi 51 , 1290 Versoix , Switzerland

34. A. Erikson

    Deutsches Zentrum für Luft- und Raumfahrt e. V. (DLR)

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    Institute of Planetary Research , German Aerospace Center (DLR) , Rutherfordstrasse 2 , 12489 Berlin , Germany

35. A. Fortier

    University of Bern · Center for Space and Habitability

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    Center for Space and Habitability , University of Bern , Gesellschaftsstrasse 6 , 3012 Bern , Switzerland

    Space Research and Planetary Sciences , Physics Institute , Univer- sity of Bern , Gesellschaftsstrasse 6 , 3012 Bern , Switzerland

36. L. Fossati

    Austrian Academy of Sciences · Space Research Institute

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    Space Research Institute , Austrian Academy of Sciences , Schmiedlstrasse 6 , A-8042 Graz , Austria

37. M. Fridlund Aachen Leiden Observatory

    Leiden University · Leiden Observatory · Chalmers University of Technology

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    Department of Space, Earth and Environment , Chalmers University of Technology , Onsala Space Observatory , 439 92 Onsala , Sweden

    Leiden Observatory , University of Leiden , PO Box 9513 , 2300 RA Leiden , The Netherlands

38. K. Gazeas

    National and Kapodistrian University of Athens

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    National and Kapodistrian University of Athens , Department of Physics , University Campus , Zografos GR-157 84 , Athens , Greece

39. M. Gillon

    University of Liège

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    Astrobiology Research Unit , Université de Liège , Allée du 6 Août 19C , B-4000 Liège , Belgium

40. M. Güdel
41. P. Guterman

    Centre National de la Recherche Scientifique · Aix-Marseille Université · Laboratoire d’Astrophysique de Marseille

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    Aix Marseille Univ , CNRS , CNES , LAM , 38 rue Frédéric Joliot- Curie , 13388 Marseille , France

42. Ch. Helling
43. K. G. Isaak

    European Space Agency · European Space Research and Technology Centre

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    European Space Agency (ESA) , European Space Research and Technology Centre (ESTEC) , Keplerlaan 1 , 2201 AZ Noordwijk , The Netherlands

44. L. L. Kiss
45. Emanuel Kopp
46. J. Korth
47. K. W. F. Lam

    Deutsches Zentrum für Luft- und Raumfahrt e. V. (DLR)

    Affiliation as printed

    Institute of Planetary Research , German Aerospace Center (DLR) , Rutherfordstrasse 2 , 12489 Berlin , Germany

48. J. Laskar
49. Alain Lecavelier des Etangs
50. A. Luntzer

    Eötvös Loránd University · Centre National de la Recherche Scientifique · Konkoly Observatory · Graz University of Technology

    Affiliation as printed

    Department of Astrophysics, University of Vienna, Türkenschanzs- trasse 17, 1180 Vienna, Austria 34 Division Technique INSU, CS20330, 83507 La Seyne sur Mer cedex, France 35 Institute for Theoretical Physics and Computational Physics, Graz University of Technology, Petersgasse 16, 8010 Graz, Austria 36 Konkoly Observatory, Research Centre for Astronomy and Earth Sciences, 1121 Budapest, Konkoly Thege Miklós út 15-17, Hungary 37 ELTE Eötvös Loránd University, Institute of Physics, Pázmány Péter sétány 1/A, 1117 Budapest, Hungary 38 Lund Observatory, Division of Astrophysics, Department of Physics, Lund University, Box 118, 22100 Lund, Sweden 39 IMCCE, UMR8028 CNRS, Observatoire de Paris, PSL Univ., Sor- bonne Univ., 77 av. Denfert-Rochereau, 75014 Paris, France 40 Institut d'astrophysique de Paris, UMR7095 CNRS, Université Pierre & Marie Curie, 98bis blvd. Arago, 75014 Paris, France 41 Astrophysics Group, Lennard Jones Building, Keele University, Staffordshire, ST5 5BG, United Kingdom 4

51. Demetrio Magrin

    Osservatorio Astronomico di Padova · National Institute for Astrophysics

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52. G. Mantovan
53. L. Marafatto

    Osservatorio Astronomico di Padova · National Institute for Astrophysics

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    INAF , Osservatorio Astronomico di Padova , Vicolo dell'Osservatorio 5 , 35122 Padova , Italy

54. P. F. L. Maxted
55. Bruno Merín
56. C. Mordasini

    University of Bern · Center for Space and Habitability

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    Center for Space and Habitability , University of Bern , Gesellschaftsstrasse 6 , 3012 Bern , Switzerland

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57. Matteo Munari
58. V. Nascimbeni

    Osservatorio Astronomico di Padova · National Institute for Astrophysics

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    INAF , Osservatorio Astronomico di Padova , Vicolo dell'Osservatorio 5 , 35122 Padova , Italy

59. Göran Olofsson

    Stockholm University · AlbaNova

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    Department of Astronomy , Stockholm University , AlbaNova Uni- versity Center , 10691 Stockholm , Sweden

60. R. Ottensamer

    Eötvös Loránd University · Centre National de la Recherche Scientifique · Konkoly Observatory · Graz University of Technology

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    Department of Astrophysics, University of Vienna, Türkenschanzs- trasse 17, 1180 Vienna, Austria 34 Division Technique INSU, CS20330, 83507 La Seyne sur Mer cedex, France 35 Institute for Theoretical Physics and Computational Physics, Graz University of Technology, Petersgasse 16, 8010 Graz, Austria 36 Konkoly Observatory, Research Centre for Astronomy and Earth Sciences, 1121 Budapest, Konkoly Thege Miklós út 15-17, Hungary 37 ELTE Eötvös Loránd University, Institute of Physics, Pázmány Péter sétány 1/A, 1117 Budapest, Hungary 38 Lund Observatory, Division of Astrophysics, Department of Physics, Lund University, Box 118, 22100 Lund, Sweden 39 IMCCE, UMR8028 CNRS, Observatoire de Paris, PSL Univ., Sor- bonne Univ., 77 av. Denfert-Rochereau, 75014 Paris, France 40 Institut d'astrophysique de Paris, UMR7095 CNRS, Université Pierre & Marie Curie, 98bis blvd. Arago, 75014 Paris, France 41 Astrophysics Group, Lennard Jones Building, Keele University, Staffordshire, ST5 5BG, United Kingdom 4

61. I. Pagano
62. Ε. Πάλλη
63. Gisbert Peter
64. D. Piazza
65. G. Piotto

    Osservatorio Astronomico di Padova · National Institute for Astrophysics

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66. D. Pollacco

    University of Warwick

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    Department of Physics , University of Warwick , Gibbet Hill Road , Coventry CV4 7AL , United Kingdom

67. K. Poppenhaeger
68. D. Queloz
69. Roberto Ragazzoni

    Osservatorio Astronomico di Padova · National Institute for Astrophysics

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70. N. Rando

    European Space Agency · European Space Research and Technology Centre

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    European Space Agency (ESA) , European Space Research and Technology Centre (ESTEC) , Keplerlaan 1 , 2201 AZ Noordwijk , The Netherlands

71. Heike Rauer

    Deutsches Zentrum für Luft- und Raumfahrt e. V. (DLR)

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    Institute of Planetary Research , German Aerospace Center (DLR) , Rutherfordstrasse 2 , 12489 Berlin , Germany

72. I. Ribas
73. M. Rieder

    University of Bern · Center for Space and Habitability

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74. N.C. Santos

    Universidade do Porto · Institute of Astrophysics and Space Sciences · Centro de Astrofísica da Universidade do Porto

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    Departamento de Fisica e Astronomia , Faculdade de Ciencias , Uni- versidade do Porto , Rua do Campo Alegre , 4169-007 Porto , Portugal

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75. G. Scandariato
76. D. Ségransan
77. A. E. Simon

    University of Bern · Center for Space and Habitability

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78. S. G. Sousa

    Universidade do Porto · Institute of Astrophysics and Space Sciences · Centro de Astrofísica da Universidade do Porto

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79. Richard T. Southworth
80. M. Stalport

    University of Liège

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81. S. Sulis

    Centre National de la Recherche Scientifique · Aix-Marseille Université · Laboratoire d’Astrophysique de Marseille

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    Aix Marseille Univ , CNRS , CNES , LAM , 38 rue Frédéric Joliot- Curie , 13388 Marseille , France

82. S. Udry

    University of Geneva

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83. Soléne Ulmer-Moll

    University of Geneva · University of Bern

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84. V. Van Grootel
85. J. Venturini

    University of Geneva

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86. E. Villaver

    Universidad de La Laguna · Instituto de Astrofísica de Canarias

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    Departamento de Astrofísica , Universidad de La Laguna , As- trofísico Francisco Sanchez s/n , 38206 La Laguna , Tenerife , Spain

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87. N. A. Walton
88. T. Zingales

    Osservatorio Astronomico di Padova · National Institute for Astrophysics

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