Transit-timing variations in the AU Mic system observed with CHEOPS
Artikel i vetenskaplig tidskrift, 2025
Context. AU Mic is a very active M dwarf star with an edge-on debris disk and two known transiting sub-Neptunes with a possible third planetary companion. The two transiting planets exhibit significant transit-timing variations (TTVs) that are caused by the gravi tational interaction between the bodies in the system. Aims. Using photometrical observations taken with the CHaracterizing ExOPlanet Satellite (CHEOPS), we aim to constrain the plan etary radii, the orbital distances, and the periods of AU Mic b and c. Furthermore, our goal is to determine the superperiod of the TTVs for AU Mic b and to update the transit ephemeris for both planets. Additionally, based on the perceived TTVs, we study the possible presence of a third planet in the system. Methods. We conducted ultra-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. Results. We found that 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 spots on the stellar surface. AU Mic c showed very strong TTVs, with transits that occurred ∼80 minutes later in 2023 than in 2021. Through a 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 0.2030.024+0.022 MO. We explored the orbital geometry of the system and found that AU Mic c has a misaligned retrograde orbit. The limited number of AU Mic observations prevented us from determining the exact dynamical configuration and planetary parameters. Further monitoring of the system with CHEOPS might help to improve these results.
Planets and satellites: fundamental parameters
Författare
Boldog
Eötvös Loránd University (ELTE)
CSILLAGASZATI ES FOLDTUDOMANYI KUTATOKOZPONT (CSFK)
Magyar Tudomanyos Akademia
G.M. Szabó
Eötvös Loránd University (ELTE)
L. Kriskovics
CSILLAGASZATI ES FOLDTUDOMANYI KUTATOKOZPONT (CSFK)
Magyar Tudomanyos Akademia
L. Borsato
Istituto nazionale di astrofisica (INAF)
D. Gandolfi
Universita degli Studi di Torino
M. Lendl
Université de Genève
Maximilian N. Günther
Europeiska rymdorganisationen (ESA)
A. Heitzmann
Université de Genève
T.G. Wilson
The University of Warwick
A. Brandeker
Stockholms universitet
Z. Garai
Slovak Academy of Sciences
Eötvös Loránd University (ELTE)
Y. Alibert
Universität Bern
R. Alonso
Instituto de Astrofísica de Canarias
Universidad de la Laguna
T. Bárczy
Admatis
D. Barrado Navascues
Centro de Astrobiologia (CAB)
S.C.C. Barros
Universidade do Porto
W. Baumjohann
Institut fur Weltraumforschung
W. Benz
Universität Bern
N. Billot
Université de Genève
C. Broeg
Universität Bern
A. Collier Cameron
University of St Andrews
A. Correia
Universidade de Coimbra
Szilard Csizmadia
Deutsches Zentrums für Luft- und Raumfahrt (DLR)
P. E. Cubillos
Istituto nazionale di astrofisica (INAF)
Institut fur Weltraumforschung
Melvyn B. Davies
Lunds universitet
M. Deleuil
Laboratoire d'Astrophysique de Marseille
A. Deline
Université de Genève
O. Demangeon
Universidade do Porto
B.O. Demory
Universität Bern
A. Derekas
Eötvös Loránd University (ELTE)
Billy Edwards
Netherlands Institute for Space Research (SRON)
J. A. Egger
Universität Bern
D. Ehrenreich
Université de Genève
Anders Erikson
Deutsches Zentrums für Luft- und Raumfahrt (DLR)
A. Fortier
Universität Bern
L. Fossati
Institut fur Weltraumforschung
Malcolm Fridlund
Chalmers, Rymd-, geo- och miljövetenskap, Astronomi och plasmafysik
Universiteit Leiden
K. Gazeas
University of Athens
Michaël Gillon
Universite de Liège
M. Gudel
Universität Wien
P. Guterman
Division Technique de I'INSU
Laboratoire d'Astrophysique de Marseille
Ch. Helling
Technische Universität Graz
Institut fur Weltraumforschung
K. Isaak
Europeiska rymdorganisationen (ESA)
L. L. Kiss
Eötvös Loránd University (ELTE)
Magyar Tudomanyos Akademia
E. Kopp
Deutsches Zentrums für Luft- und Raumfahrt (DLR)
Judith Korth
Lunds universitet
K. W.F. Lam
Deutsches Zentrums für Luft- und Raumfahrt (DLR)
J. Laskar
Observatoire de Paris
A. L. des Etangs
Institut d 'Astrophysique de Paris
A. Luntzer
Universität Wien
D. Magrin
Istituto nazionale di astrofisica (INAF)
G. Mantovan
Università di Padova
L. Marafatto
Istituto nazionale di astrofisica (INAF)
P. Maxted
Keele University
Bruno Merín
Europeiska rymdorganisationen (ESA)
C. Mordasini
Universität Bern
M. Munari
Istituto nazionale di astrofisica (INAF)
Valerio Nascimbeni
Istituto nazionale di astrofisica (INAF)
G. Olofsson
Stockholms universitet
R. Ottensamer
Universität Wien
I. Pagano
Istituto nazionale di astrofisica (INAF)
Enric Palle
Universidad de la Laguna
Instituto de Astrofísica de Canarias
G. Peter
Deutsches Zentrums für Luft- und Raumfahrt (DLR)
D. Piazza
Universität Bern
Giampaolo P. Piotto
Istituto nazionale di astrofisica (INAF)
Università di Padova
Don L. Pollacco
The University of Warwick
K. Poppenhaeger
Leibniz-Gemeinschaft
D. Queloz
Eidgenössische Technische Hochschule Zürich (ETH)
University of Cambridge
Roberto Ragazzoni
Istituto nazionale di astrofisica (INAF)
Università di Padova
N. Rando
Europeiska rymdorganisationen (ESA)
H. Rauer
Freie Universität Berlin
Deutsches Zentrums für Luft- und Raumfahrt (DLR)
I. Ribas
Centre Tecnològic de Telecomunicacions de Catalunya (CTTC)
Consejo Superior de Investigaciones Científicas (CSIC)
M. Rieder
Universität Bern
N. C. Santos
Universidade do Porto
Gaetano Scandariato
Istituto nazionale di astrofisica (INAF)
D. Segransan
Université de Genève
A.E. Simon
Universität Bern
A. M.S. Smith
Deutsches Zentrums für Luft- und Raumfahrt (DLR)
S.G. Sousa
Universidade do Porto
R. Southworth
Europeiska rymdorganisationen (ESA)
M. Stalport
Universite de Liège
S. Sulis
Laboratoire d'Astrophysique de Marseille
S. Udry
Université de Genève
S. Ulmer-Moll
Universität Bern
Université de Genève
Universite de Liège
V. Van Grootel
Universite de Liège
J. Venturini
Université de Genève
E. Villaver
Universidad de la Laguna
Instituto de Astrofísica de Canarias
N. A. Walton
University of Cambridge
Tiziano Zingales
Università di Padova
Istituto nazionale di astrofisica (INAF)
Astronomy and Astrophysics
0004-6361 (ISSN) 1432-0746 (eISSN)
Vol. 694 A137Exoplaneter från rymden - CHEOPS och PLATO, ESA's nästa två missioner
Rymdstyrelsen (174/18), 2017-01-01 -- 2022-12-31.
Satellitstudier av exoplaneters mångfald
Rymdstyrelsen (174/18), 2019-02-04 -- 2023-08-01.
Ämneskategorier (SSIF 2025)
Astronomi, astrofysik och kosmologi
DOI
10.1051/0004-6361/202452699