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.

techniques: photometric

stars: individual: TIC 12089692

stars: individual: TOI-402

planets and satellites: composition

stars: individual: HD 15337

techniques: radial velocities

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

Instituto de Astrofísica de Canarias

University of La Laguna

G. Anglada

Centre Tecnològic de Telecomunicacions de Catalunya (CTTC)

Spanish National Research Council (CSIC)

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

Istituto nazionale di astrofisica (INAF)

Max Planck Society

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

Istituto nazionale di astrofisica (INAF)

Austrian Academy of Sciences

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

University College London (UCL)

European Southern Observatory Santiago

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

Istituto nazionale di astrofisica (INAF)

University of Padua

D. Pollacco

The University of Warwick

D. Queloz

Swiss Federal Institute of Technology in Zürich (ETH)

University of Cambridge

R. Ragazzoni

Istituto nazionale di astrofisica (INAF)

University of Padua

N. Rando

European Space Research and Technology Centre (ESA ESTEC)

H. Rauer

Freie Universität Berlin

Technische Universität Berlin

German Aerospace Center (DLR)

I. Ribas

Spanish National Research Council (CSIC)

Centre Tecnològic de Telecomunicacions de Catalunya (CTTC)

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 A282

Subject Categories (SSIF 2011)

Astronomy, Astrophysics and Cosmology

Condensed Matter Physics

DOI

10.1051/0004-6361/202347759

More information

Latest update

3/16/2025