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.

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 A301

Exoplaneter från rymden - CHEOPS och PLATO, ESA's nästa två rymdteleskop (fas 2)

Rymdstyrelsen (65/19), 2020-01-01 -- 2022-12-31.

Rymdstyrelsen (177/19), 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

Mer information

Senast uppdaterat

2024-07-26