Characterisation of the TOI-421 planetary system using CHEOPS, TESS, and archival radial velocity data
Artikel i vetenskaplig tidskrift, 2024
Context. The TOI-421 planetary system contains two sub-Neptune-type planets (Pb ~ 5.2 days, Teqb ~ 900 K, and Pc ~ 16.1 days, Teq,c ~ 650 K) and is a prime target to study the formation and evolution of planets and their atmospheres. The inner planet is especially interesting as the existence of a hydrogen-dominated atmosphere at its orbital separation cannot be explained by current formation models without previous orbital migration. Aims. We aim to improve the system parameters to further use them to model the interior structure and simulate the atmospheric evolution of both planets, to finally gain insights into their formation and evolution. We also investigate the possibility of detecting transit timing variations (TTVs).
Methods. We jointly analysed photometric data of three TESS sectors and six CHEOPS visits as well as 156 radial velocity data points to retrieve improved planetary parameters. We also searched for TTVs and modelled the interior structure of the planets. Finally, we simulated the evolution of the primordial H-He atmospheres of the planets using two different modelling frameworks.
Results. We determine the planetary radii and masses of TOI-421 b and c to be Rb = 2.64 ± 0.08 R, Mb = 6.7 ± 0.6 M, Rc = 5.09 ± 0.07 R, and Mc = 14.1 ± 1.4 M. Using these results we retrieved average planetary densities of ρb = 0.37 ± 0.05ρ and ρc = 0.107 ± 0.012 ρ. We do not detect any statistically significant TTV signals. Assuming the presence of a hydrogen-dominated atmosphere, the interior structure modelling results in both planets having extensive envelopes. While the modelling of the atmospheric evolution predicts for TOI-421 b to have lost any primordial atmosphere that it could have accreted at its current orbital position, TOI-421 c could have started out with an initial atmospheric mass fraction somewhere between 10 and 35%.
Conclusions. We conclude that the low observed mean density of TOI-421 b can only be explained by either a bias in the measured planetary parameters (e.g. driven by high-altitude clouds) and/or in the context of orbital migration. We also find that the results of atmospheric evolution models are strongly dependent on the employed planetary structure model.
Methods. We jointly analysed photometric data of three TESS sectors and six CHEOPS visits as well as 156 radial velocity data points to retrieve improved planetary parameters. We also searched for TTVs and modelled the interior structure of the planets. Finally, we simulated the evolution of the primordial H-He atmospheres of the planets using two different modelling frameworks.
Results. We determine the planetary radii and masses of TOI-421 b and c to be Rb = 2.64 ± 0.08 R, Mb = 6.7 ± 0.6 M, Rc = 5.09 ± 0.07 R, and Mc = 14.1 ± 1.4 M. Using these results we retrieved average planetary densities of ρb = 0.37 ± 0.05ρ and ρc = 0.107 ± 0.012 ρ. We do not detect any statistically significant TTV signals. Assuming the presence of a hydrogen-dominated atmosphere, the interior structure modelling results in both planets having extensive envelopes. While the modelling of the atmospheric evolution predicts for TOI-421 b to have lost any primordial atmosphere that it could have accreted at its current orbital position, TOI-421 c could have started out with an initial atmospheric mass fraction somewhere between 10 and 35%.
Conclusions. We conclude that the low observed mean density of TOI-421 b can only be explained by either a bias in the measured planetary parameters (e.g. driven by high-altitude clouds) and/or in the context of orbital migration. We also find that the results of atmospheric evolution models are strongly dependent on the employed planetary structure model.
Planets and satellites: composition
Planets and satellites: fundamental parameters
Planets and satellites: individual: TOI-421
Författare
A. Krenn
Institut fur Weltraumforschung
D. Kubyshkina
Institut fur Weltraumforschung
L. Fossati
Institut fur Weltraumforschung
J. A. Egger
Universität Bern
A. Bonfanti
Institut fur Weltraumforschung
A. Deline
Université de Genève
D. Ehrenreich
Université de Genève
M. Beck
Université de Genève
W. Benz
Universität Bern
J. Cabrera
Deutsches Zentrums für Luft- und Raumfahrt (DLR)
T.G. Wilson
University of St Andrews
A. Leleu
Universität Bern
Université de Genève
S.G. Sousa
Universidade do Porto
V. Adibekyan
Universidade do Porto
A. Correia
Centre for Physics of the University of Coimbra
Y. Alibert
Universität Bern
L. Delrez
Universite de Liège
M. Lendl
Université de Genève
J. A. Patel
Stockholms universitet
J. Venturini
Université de Genève
R. Alonso
Instituto de Astrofísica de Canarias
Universidad de la Laguna
G. Anglada
Institut d'Estudis Espacials de Catalunya (IEEC)
Institut de Ciències de l'Espai (ICE) - CSIC
J. Asquier
European Space Research and Technology Centre (ESA ESTEC)
T. Bárczy
Admatis
D. Barrado Navascues
European Space Astronomy Centre (ESAC)
S.C.C. Barros
Universidade do Porto
W. Baumjohann
Institut fur Weltraumforschung
T. Beck
Universität Bern
N. Billot
Université de Genève
X. Bonfils
Institut de Planétologie et d’Astrophysique de Grenoble (IPAG)
L. Borsato
Istituto nazionale di astrofisica (INAF)
A. Brandeker
Stockholms universitet
C. Broeg
Universität Bern
S. Charnoz
Institut de Physique du Globe de Paris
A. Collier Cameron
University of St Andrews
Szilard Csizmadia
Deutsches Zentrums für Luft- und Raumfahrt (DLR)
P. E. Cubillos
Istituto nazionale di astrofisica (INAF)
Institut fur Weltraumforschung
M. B. Davies
Lunds universitet
M. Deleuil
Laboratoire d'Astrophysique de Marseille
O. Demangeon
Universidade do Porto
B.O. Demory
Universität Bern
Anders Erikson
Deutsches Zentrums für Luft- und Raumfahrt (DLR)
A. Fortier
Universität Bern
Malcolm Fridlund
Universiteit Leiden
Chalmers, Rymd-, geo- och miljövetenskap, Astronomi och plasmafysik
D. Gandolfi
Universita degli Studi di Torino
Michaël Gillon
Universite de Liège
M. Gudel
Universität Wien
Maximilian N. Günther
European Space Research and Technology Centre (ESA ESTEC)
J. Hasiba
Institut fur Weltraumforschung
A. Heitzmann
Université de Genève
Ch. Helling
Technische Universität Graz
Institut fur Weltraumforschung
S. Hoyer
Laboratoire d'Astrophysique de Marseille
K. Isaak
European Space Research and Technology Centre (ESA ESTEC)
L. L. Kiss
Eötvös Loránd University (ELTE)
Magyar Tudomanyos Akademia
K. W.F. Lam
Deutsches Zentrums für Luft- und Raumfahrt (DLR)
J. Laskar
Observatoire de Paris
A. L. des Etangs
Centre national de la recherche scientifique (CNRS)
C. Lovis
Université de Genève
D. Magrin
Istituto nazionale di astrofisica (INAF)
P. Maxted
Keele University
C. Mordasini
Universität Bern
Valerio Nascimbeni
Istituto nazionale di astrofisica (INAF)
G. Olofsson
Stockholms universitet
R. Ottensamer
Universität Wien
I. Pagano
Istituto nazionale di astrofisica (INAF)
Enric Palle
Instituto de Astrofísica de Canarias
Universidad de la Laguna
G. Peter
Deutsches Zentrums für Luft- und Raumfahrt (DLR)
Giampaolo P. Piotto
Istituto nazionale di astrofisica (INAF)
Università di Padova
Don L. Pollacco
The University of Warwick
D. Queloz
Eidgenössische Technische Hochschule Zürich (ETH)
University of Cambridge
Roberto Ragazzoni
Istituto nazionale di astrofisica (INAF)
Università di Padova
N. Rando
European Space Research and Technology Centre (ESA ESTEC)
H. Rauer
Technische Universität Berlin
Deutsches Zentrums für Luft- und Raumfahrt (DLR)
Freie Universität Berlin
I. Ribas
Institut de Ciències de l'Espai (ICE) - CSIC
Institut d'Estudis Espacials de Catalunya (IEEC)
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)
M. Stalport
Universite de Liège
Manfred B. Steller
Institut fur Weltraumforschung
Gy M. Szabó
Eötvös Loránd University (ELTE)
Nicolas Thomas
Universität Bern
S. Udry
Université de Genève
B. Ulmer
Deutsches Zentrums für Luft- und Raumfahrt (DLR)
V. Van Grootel
Universite de Liège
E. Villaver
Universidad de la Laguna
Instituto de Astrofísica de Canarias
V. Viotto
Istituto nazionale di astrofisica (INAF)
N. A. Walton
University of Cambridge
Tiziano Zingales
Istituto nazionale di astrofisica (INAF)
Università di Padova
Astronomy and Astrophysics
0004-6361 (ISSN) 1432-0746 (eISSN)
Vol. 686 A301Exoplaneter från rymden - CHEOPS och PLATO, ESA's nästa två rymdteleskop (fas 2)
Rymdstyrelsen (177/19), 2020-01-01 -- 2022-12-31.
Rymdstyrelsen (65/19), 2020-01-01 -- 2022-12-31.
Exoplaneter från rymden - CHEOPS och PLATO, ESA's nästa två missioner
Rymdstyrelsen (174/18), 2017-01-01 -- 2022-12-31.
Ämneskategorier
Meteorologi och atmosfärforskning
Astronomi, astrofysik och kosmologi
Atom- och molekylfysik och optik
DOI
10.1051/0004-6361/202348584