Precise characterisation of HD 15337 with CHEOPS: A laboratory for planet formation and evolution
Journal article, 2024
Context. The HD 15337 (TIC 120896927, TOI-402) system was observed by the Transiting Exoplanet Survey Satellite (TESS), revealing the presence of two short-period planets situated on opposite sides of the radius gap. This offers an excellent opportunity to study theories of formation and evolution, as well as to investigate internal composition and atmospheric evaporation.
Aims. We aim to constrain the internal structure and composition of two short-period planets situated on opposite sides of the radius valley: HD 15337 b and c. We use new transit photometry and radial velocity data.
Methods. We acquired 6 new transit visits with the CHaracterising ExOPlanet Satellite (CHEOPS) and 32 new radial velocity measurements from the High Accuracy Radial Velocity Planet Searcher (HARPS) to improve the accuracy of the mass and radius estimates for both planets. We re-analysed the light curves from TESS sectors 3 and 4 and analysed new data from sector 30, correcting for long-term stellar activity. Subsequently, we performed a joint fit of the TESS and CHEOPS light curves, along with all available RV data from HARPS and the Planet Finder Spectrograph (PFS). Our model fit the planetary signals, stellar activity signal, and instrumental decorrelation model for the CHEOPS data simultaneously. The stellar activity was modelled using a Gaussian-process regression on both the RV and activity indicators. Finally, we employed a Bayesian retrieval code to determine the internal composition and structure of the planets.
Results. We derived updated and highly precise parameters for the HD 15337 system. Our improved precision on the planetary parameters makes HD 15337 b one of the most precisely characterised rocky exoplanets, with radius and mass measurements achieving a precision better than 2% and 7%, respectively. We were able to improve the precision of the radius measurement of HD 15337 c to 3%. Our results imply that the composition of HD 15337 b is predominantly rocky, while HD 15337 c exhibits a gas envelope with a mass of at least 0.01 M-circle plus.
Conclusions. Our results lay the groundwork for future studies, which can further unravel the atmospheric evolution of these exoplanets and offer new insights into their composition and formation history as well as the causes behind the radius gap.
Aims. We aim to constrain the internal structure and composition of two short-period planets situated on opposite sides of the radius valley: HD 15337 b and c. We use new transit photometry and radial velocity data.
Methods. We acquired 6 new transit visits with the CHaracterising ExOPlanet Satellite (CHEOPS) and 32 new radial velocity measurements from the High Accuracy Radial Velocity Planet Searcher (HARPS) to improve the accuracy of the mass and radius estimates for both planets. We re-analysed the light curves from TESS sectors 3 and 4 and analysed new data from sector 30, correcting for long-term stellar activity. Subsequently, we performed a joint fit of the TESS and CHEOPS light curves, along with all available RV data from HARPS and the Planet Finder Spectrograph (PFS). Our model fit the planetary signals, stellar activity signal, and instrumental decorrelation model for the CHEOPS data simultaneously. The stellar activity was modelled using a Gaussian-process regression on both the RV and activity indicators. Finally, we employed a Bayesian retrieval code to determine the internal composition and structure of the planets.
Results. We derived updated and highly precise parameters for the HD 15337 system. Our improved precision on the planetary parameters makes HD 15337 b one of the most precisely characterised rocky exoplanets, with radius and mass measurements achieving a precision better than 2% and 7%, respectively. We were able to improve the precision of the radius measurement of HD 15337 c to 3%. Our results imply that the composition of HD 15337 b is predominantly rocky, while HD 15337 c exhibits a gas envelope with a mass of at least 0.01 M-circle plus.
Conclusions. Our results lay the groundwork for future studies, which can further unravel the atmospheric evolution of these exoplanets and offer new insights into their composition and formation history as well as the causes behind the radius gap.
planets and satellites: composition
techniques: photometric
stars: individual: TOI-402
techniques: radial velocities
stars: individual: TIC 12089692
stars: individual: HD 15337
Author
N. M. Rosario
University of Porto
O. D. S. Demangeon
University of Porto
S. C. C. Barros
University of Porto
D. Gandolfi
University of Turin
J. A. Egger
University of Bern
L. M. Serrano
University of Turin
H. P. Osborn
Massachusetts Institute of Technology (MIT)
University of Bern
M. Beck
University of Geneva
W. Benz
University of Bern
H. -G. Floren
Stockholm University
P. Guterman
Aix Marseille University
Institut National des Sciences de l'Univers
T. G. Wilson
The University of Warwick
University of St Andrews
Y. Alibert
University of Bern
L. Fossati
Austrian Academy of Sciences
M. J. Hooton
University of Cambridge
L. Delrez
University of Liège
N. C. Santos
University of Porto
S. G. Sousa
University of Porto
A. Bonfanti
Austrian Academy of Sciences
S. Salmon
University of Geneva
V. Adibekyan
University of Porto
A. Nigioni
University of Geneva
J. Venturini
University of Geneva
R. Alonso
University of La Laguna
Instituto de Astrofísica de Canarias
G. Anglada
Spanish National Research Council (CSIC)
Institute of Space Studies of Catalonia (IEEC)
J. Asquier
European Space Research and Technology Centre (ESA ESTEC)
T. Barczy
Admatis
D. Barrado Navascues
Spanish National Research Council (CSIC)
O. Barragan
University of Oxford
W. Baumjohann
Austrian Academy of Sciences
T. Beck
University of Bern
N. Billot
University of Geneva
F. Biondi
Max Planck Institute for Extraterrestrial Physics
Istituto nazionale di astrofisica (INAF)
X. Bonfils
Grenoble Alpes University
L. Borsato
Istituto nazionale di astrofisica (INAF)
A. Brandeker
Stockholm University
C. Broeg
University of Bern
V. Cessa
University of Bern
S. Charnoz
Paris Cité University
A. Collier Cameron
University of St Andrews
Sz. Csizmadia
German Aerospace Center (DLR)
P. E. Cubillos
Austrian Academy of Sciences
Istituto nazionale di astrofisica (INAF)
M. B. Davies
Lund University
M. Deleuil
Aix Marseille University
A. Deline
University of Geneva
B. -O. Demory
University of Bern
D. Ehrenreich
University of Geneva
A. Erikson
German Aerospace Center (DLR)
M. Esposito
Thüringer Landessternwarte Tautenburg
A. Fortier
University of Bern
Malcolm Fridlund
Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics
M. Gillon
University of Liège
M. Guedel
University of Vienna
M. N. Gunther
European Space Research and Technology Centre (ESA ESTEC)
Ch. Helling
Austrian Academy of Sciences
S. Hoyer
Aix Marseille University
K. G. Isaak
European Space Research and Technology Centre (ESA ESTEC)
L. L. Kiss
Eötvös Loránd University (ELTE)
Konkoly Observatory
K. W. F. Lam
German Aerospace Center (DLR)
J. Laskar
Sorbonne University
A. Lecavelier des Etangs
Pierre and Marie Curie University (UPMC)
M. Lendl
University of Geneva
A. Luntzer
Vienna University of Technology
D. Magrin
Istituto nazionale di astrofisica (INAF)
P. F. L. Maxted
Keele University
C. Mordasini
University of Bern
V. Nascimbeni
Istituto nazionale di astrofisica (INAF)
G. Olofsson
Stockholm University
H. L. M. Osborne
European Southern Observatory Santiago
University College London (UCL)
R. Ottensamer
University of Vienna
I. Pagano
Istituto nazionale di astrofisica (INAF)
E. Palle
Instituto de Astrofísica de Canarias
University of La Laguna
G. Peter
German Aerospace Center (DLR)
G. Piotto
University of Padua
Istituto nazionale di astrofisica (INAF)
D. Pollacco
The University of Warwick
D. Queloz
Swiss Federal Institute of Technology in Zürich (ETH)
University of Cambridge
R. Ragazzoni
University of Padua
Istituto nazionale di astrofisica (INAF)
N. Rando
European Space Research and Technology Centre (ESA ESTEC)
H. Rauer
Freie Universität Berlin
German Aerospace Center (DLR)
Technische Universität Berlin
I. Ribas
Institute of Space Studies of Catalonia (IEEC)
Spanish National Research Council (CSIC)
G. 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
Gy. M. Szabo
Eötvös Loránd University (ELTE)
N. Thomas
University of Bern
S. Udry
University of Geneva
V. Van Eylen
University College London (UCL)
V. Van Grootel
University of Liège
E. Villaver
Instituto de Astrofísica de Canarias
I. Walter
German Aerospace Center (DLR)
N. A. Walton
University of Cambridge
Astronomy and Astrophysics
0004-6361 (ISSN) 1432-0746 (eISSN)
Vol. 686 A282Subject Categories
Astronomy, Astrophysics and Cosmology
Condensed Matter Physics
DOI
10.1051/0004-6361/202347759