Photo-dynamical characterisation of the TOI-178 resonant chain: Exploring the robustness of transit-timing variations and radial velocity mass characterisations
Journal article, 2024
Context. The TOI-178 system consists of a nearby, late-K-dwarf with six transiting planets in the super-Earth to mini-Neptune regime, with radii ranging from ∼1.1 to 2.9 R⊕ and orbital periods between 1.9 and 20.7 days. All the planets, but the innermost one, form a chain of Laplace resonances. The fine-tuning and fragility of such orbital configurations ensure that no significant scattering or collision event has taken place since the formation and migration of the planets in the protoplanetary disc, thereby providing important anchors for planet formation models. Aims. We aim to improve the characterisation of the architecture of this key system and, in particular, the masses and radii of its planets. In addition, since this system is one of the few resonant chains that can be characterised by both photometry and radial velocities, we propose to use it as a test bench for the robustness of the planetary mass determination with each technique. Methods. We performed a global analysis of all the available photometry from CHEOPS, TESS and NGTS, and radial velocity from ESPRESSO, using a photo-dynamical modelling of the light curve.We also tried different sets of priors on the masses and eccentricity, as well as different stellar activity models, to study their effects on the masses estimated by transit-timing variations (TTVs) and radial velocities (RVs). Results. We demonstrate how stellar activity prevents a robust mass estimation for the three outer planets using radial velocity data alone.We also show that our joint photo-dynamical and radial velocity analysis has resulted in a robust mass determination for planets c to g, with precision of ∼12% for the mass of planet c, and better than 10% for planets d to g. The new precisions on the radii range from 2 to 3%. The understanding of this synergy between photometric and radial velocity measurements will be valuable for the PLATO mission. We also show that TOI-178 is indeed currently locked in the resonant configuration, librating around an equilibrium of the chain.
Techniques: radial velocities
Techniques: photometric
Planets and satellites: gaseous planets
Methods: data analysis
Planets and satellites: detection
Author
A. Leleu
University of Geneva
J. B. Delisle
University of Geneva
L. Delrez
University of Liège
E. Bryant
University College London (UCL)
A. Brandeker
Stockholm University
H. P. Osborn
University of Bern
N.C. Hara
University of Geneva
T.G. Wilson
The University of Warwick
N. Billot
University of Geneva
M. Lendl
University of Geneva
D. Ehrenreich
University of Geneva
Hritam Chakraborty
University of Geneva
Maximilian N. Günther
European Space Agency (ESA)
M.J. Hooton
University of Cambridge
Y. Alibert
Physics Institute
R. Alonso
Instituto de Astrofísica de Canarias
Douglas R. Alves
University of Chile (UCH)
D. Anderson
Universidad Catolica del Norte
I. Apergis
The University of Warwick
D. J. Armstrong
The University of Warwick
T. Bárczy
Admatis
D. Barrado
Centro de Astrobiologia (CAB)
S.C.C. Barros
University of Porto
M. P. Battley
University of Geneva
W. Baumjohann
Institut fur Weltraumforschung
D. Bayliss
The University of Warwick
T. Beck
University of Bern
W. Benz
University of Bern
L. Borsato
Istituto nazionale di astrofisica (INAF)
C. Broeg
Physics Institute
Matt Burleigh
University Of Leicester
Sarah Casewell
University Of Leicester
A. Collier Cameron
University of St Andrews
A. Correia
University of Coimbra
Szilard Csizmadia
German Aerospace Center (DLR)
P. E. Cubillos
Institut fur Weltraumforschung
Melvyn B. Davies
Lund University
M. Deleuil
Laboratoire d'Astrophysique de Marseille
A. Deline
University of Geneva
O. Demangeon
University of Porto
B.O. Demory
University of Bern
A. Derekas
Eötvös Loránd University (ELTE)
Billy Edwards
Netherlands Institute for Space Research (SRON)
Anders Erikson
German Aerospace Center (DLR)
A. Fortier
University of Bern
L. Fossati
Institut fur Weltraumforschung
Malcolm Fridlund
Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics
Leiden University
D. Gandolfi
University of Turin
K. Gazeas
University of Athens
E. Gillen
Queen Mary University of London
Michaël Gillon
University of Liège
M.R. Goad
University Of Leicester
M. Gudel
University of Vienna
F. Hawthorn
The University of Warwick
A. Heitzmann
University of Geneva
Ch. Helling
Institut fur Weltraumforschung
K. Isaak
European Space Agency (ESA)
James S. Jenkins
Diego Portales University
Jon M. Jenkins
National Aeronautics and Space Administration (NASA)
Alicia Kendall
University Of Leicester
L. L. Kiss
Hungarian Academy of Sciences
Judith Korth
Lund University
K. W.F. Lam
German Aerospace Center (DLR)
J. Laskar
Paris Observatory
D. W. Latham
Harvard-Smithsonian Center for Astrophysics
A. L. des Etangs
Institut d 'Astrophysique de Paris
D. Magrin
Istituto nazionale di astrofisica (INAF)
P. Maxted
Keele University
J. McCormac
The University of Warwick
C. Mordasini
University of Bern
M. Moyano
Universidad Catolica del Norte
Valerio Nascimbeni
Istituto nazionale di astrofisica (INAF)
G. Olofsson
Stockholm University
A. Osborn
McMaster University
R. Ottensamer
University of Vienna
I. Pagano
Istituto nazionale di astrofisica (INAF)
Enric Palle
Instituto de Astrofísica de Canarias
G. Peter
German Aerospace Center (DLR)
Giampaolo P. Piotto
Istituto nazionale di astrofisica (INAF)
Don L. Pollacco
The University of Warwick
D. Queloz
University of Cambridge
Roberto Ragazzoni
Istituto nazionale di astrofisica (INAF)
N. Rando
European Space Agency (ESA)
H. Rauer
German Aerospace Center (DLR)
I. Ribas
Spanish National Research Council (CSIC)
George R. Ricker
Massachusetts Institute of Technology (MIT)
S. Saha
Diego Portales University
N. C. Santos
University of Porto
Gaetano Scandariato
Istituto nazionale di astrofisica (INAF)
S. Seager
Massachusetts Institute of Technology (MIT)
D. Segransan
University of Geneva
A.E. Simon
University of Bern
A. M.S. Smith
German Aerospace Center (DLR)
S.G. Sousa
University of Porto
M. Stalport
University of Liège
S. Sulis
Laboratoire d'Astrophysique de Marseille
Gy M. Szabó
Eötvös Loránd University (ELTE)
S. Udry
University of Geneva
S. Ulmer-Moll
University of Geneva
V. Van Grootel
University of Liège
Roland K. Vanderspek
Massachusetts Institute of Technology (MIT)
J. Venturini
University of Geneva
E. Villaver
Instituto de Astrofísica de Canarias
José I. Vines
Universidad Catolica del Norte
N. A. Walton
University of Cambridge
Richard G West
The University of Warwick
P. J. Wheatley
The University of Warwick
J. N. Winn
Princeton University
T. Zivave
The University of Warwick
Astronomy and Astrophysics
0004-6361 (ISSN) 1432-0746 (eISSN)
Vol. 688 A211Subject Categories (SSIF 2025)
Astronomy, Astrophysics, and Cosmology
DOI
10.1051/0004-6361/202450212