Unveiling the internal structure and formation history of the three planets transiting HIP 29442 (TOI-469) with CHEOPS
Journal article, 2024
Multiplanetary systems spanning the radius valley are ideal testing grounds for exploring the different proposed explanations for the observed bimodality in the radius distribution of close-in exoplanets. One such system is HIP 29442 (TOI-469), an evolved K0V star hosting two super-Earths and one sub-Neptune. We observed HIP 29442 with CHEOPS for a total of 9.6 days, which we modelled jointly with two sectors of TESS data to derive planetary radii of 3.410 ± 0.046, 1.551 ± 0.045, and 1.538 ± 0.049 R? for planets b, c, and d, which orbit HIP 29442 with periods of 13.6, 3.5, and 6.4 days, respectively. For planet d this value deviates by more than 3s from the median value reported in the discovery paper, leading us to conclude that caution is required when using TESS photometry to determine the radii of small planets with low per-transit signal-to-noise ratios and large gaps between observations. Given the high precision of these new radii, combining them with published RVs from ESPRESSO and HIRES provides us with ideal conditions to investigate the internal structure and formation pathways of the planets in the system. We introduced the publicly available code plaNETic, a fast and robust neural network-based Bayesian internal structure modelling framework. We then applied hydrodynamic models to explore the upper atmospheric properties of these inferred structures. Finally, we identified planetary system analogues in a synthetic population generated with the Bern model for planet formation and evolution. Based on this analysis, we find that the planets likely formed on opposing sides of the water iceline from a protoplanetary disk with an intermediate solid mass. We finally report that the observed parameters of the HIP 29442 system are compatible with a scenario where the second peak in the bimodal radius distribution corresponds to sub-Neptunes with a pure H/He envelope and with a scenario with water-rich sub-Neptunes.
planets and satellites: interiors
planets and satellites: formation
planets and satellites: individual: HIP 29442
techniques: photometric
planetary systems
Author
J. A. Egger
University of Bern
H. P. Osborn
University of Bern
Massachusetts Institute of Technology (MIT)
D. Kubyshkina
Institut fur Weltraumforschung
C. Mordasini
University of Bern
Y. Alibert
University of Bern
Maximilian N. Günther
European Space Research and Technology Centre (ESA ESTEC)
M. Lendl
University of Geneva
A. Brandeker
Stockholm University
A. Heitzmann
University of Geneva
A. Leleu
University of Geneva
University of Bern
Mario Damasso
Istituto nazionale di astrofisica (INAF)
A. Bonfanti
Institut fur Weltraumforschung
T.G. Wilson
The University of Warwick
S.G. Sousa
University of Porto
J. Haldemann
University of Bern
L. Delrez
University of Liège
KU Leuven
M.J. Hooton
University of Cambridge
Tiziano Zingales
Istituto nazionale di astrofisica (INAF)
University of Padua
R. Luque
University of Chicago
R. Alonso
University of La Laguna
Instituto de Astrofísica de Canarias
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
University of Porto
W. Baumjohann
Institut fur Weltraumforschung
W. Benz
University of Bern
N. Billot
University of Geneva
L. Borsato
Istituto nazionale di astrofisica (INAF)
C. Broeg
University of Bern
M. Buder
German Aerospace Center (DLR)
A. Castro-González
European Space Astronomy Centre (ESAC)
A. Collier Cameron
University of St Andrews
A. Correia
Centre for Physics of the University of Coimbra
D. Cortes
Airbus Group
Szilard Csizmadia
German Aerospace Center (DLR)
P. E. Cubillos
Istituto nazionale di astrofisica (INAF)
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)
D. Ehrenreich
University of Geneva
Anders Erikson
German Aerospace Center (DLR)
A. Fortier
University of Bern
L. Fossati
Institut fur Weltraumforschung
Malcolm Fridlund
Leiden University
Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics
D. Gandolfi
University of Turin
K. Gazeas
University of Athens
Michaël Gillon
University of Liège
M. Gudel
University of Vienna
Ch. Helling
Technische Universität Graz
Institut fur Weltraumforschung
K. Isaak
European Space Research and Technology Centre (ESA ESTEC)
L. L. Kiss
Eötvös Loránd University (ELTE)
Hungarian Academy of Sciences
Judith Korth
Lund University
K. W.F. Lam
German Aerospace Center (DLR)
J. Laskar
Paris Observatory
B. Lavie
University of Geneva
A. L. des Etangs
Institut d 'Astrophysique de Paris
C. Lovis
University of Geneva
A. Luntzer
University of Vienna
D. Magrin
Istituto nazionale di astrofisica (INAF)
P. Maxted
Keele University
Bruno Merín
European Space Astronomy Centre (ESAC)
M. Munari
Istituto nazionale di astrofisica (INAF)
Valerio Nascimbeni
Istituto nazionale di astrofisica (INAF)
G. Olofsson
Stockholm University
R. Ottensamer
University of Vienna
I. Pagano
Istituto nazionale di astrofisica (INAF)
Enric Palle
University of La Laguna
Instituto de Astrofísica de Canarias
G. Peter
German Aerospace Center (DLR)
D. Piazza
University of Bern
Giampaolo P. Piotto
Istituto nazionale di astrofisica (INAF)
University of Padua
Don L. Pollacco
The University of Warwick
D. Queloz
Swiss Federal Institute of Technology in Zürich (ETH)
University of Cambridge
Roberto Ragazzoni
Istituto nazionale di astrofisica (INAF)
University of Padua
N. Rando
European Space Research and Technology Centre (ESA ESTEC)
H. Rauer
Freie Universität Berlin
German Aerospace Center (DLR)
I. Ribas
Institute of Space Studies of Catalonia (IEEC)
Institute of Space Sciences (ICE) - CSIC
J. Rodrigues
University of Porto
N. C. Santos
University of Porto
Gaetano Scandariato
Istituto nazionale di astrofisica (INAF)
D. Segransan
University of Geneva
A.E. Simon
University of Bern
A. M.S. Smith
German Aerospace Center (DLR)
M. Stalport
University of Liège
S. Sulis
Laboratoire d'Astrophysique de Marseille
G.M. Szabó
Eötvös Loránd University (ELTE)
S. Udry
University of Geneva
V. Van Grootel
University of Liège
J. Venturini
University of Geneva
E. Villaver
Instituto de Astrofísica de Canarias
University of La Laguna
N. A. Walton
University of Cambridge
Astronomy and Astrophysics
0004-6361 (ISSN) 1432-0746 (eISSN)
Vol. 688 A223Exoplanets from space -CHEOPS and PLATO ESA's next two projects (Phase 2)
Swedish National Space Board (65/19), 2020-01-01 -- 2022-12-31.
Swedish National Space Board (177/19), 2020-01-01 -- 2022-12-31.
Exoplanets from space – CHEOPS and PLATO, ESA’s next two projects
Swedish National Space Board (174/18), 2017-01-01 -- 2022-12-31.
Subject Categories
Astronomy, Astrophysics and Cosmology
DOI
10.1051/0004-6361/202450472