An ultra-short period super-Earth and sub-Neptune spanning the Radius Valley orbiting the kinematic thick disc star TOI-2345
Journal article, 2025
A crucial chemical link between stars and their orbiting exoplanets is thought to exist. If universal, this connection could affect the formation and evolution of all planets. Therefore, this potential vital link needs testing by characterizing exoplanets around chemically-diverse stars. We present the discovery of two planets orbiting the metal-poor, kinematic thick-disc K-dwarf TOI-2345. TOI-2345 b is a super-Earth with a period of 1.05 d and TOI-2345 c is a sub-Neptune with a period of 21 d. In addition to the target being observed in four TESS sectors, we obtained five CHEOPS visits and 26 radial velocities from HARPS. By conducting a joint analysis of all the data, we find TOI-2345 b to have a radius of 1.504+0.047-0.044 R⊕ and a mass of 3.49 ± 0.85 M⊕; and TOI-2345 c to have a radius of 2.451+0.045-0.046 R⊕ and a mass of 7.27+2.27-2.45 M⊕. To explore chemical links between these planets and their host star, we model their interior structures newly accounting for devolatized stellar abundances. TOI-2345 adds to the limited sample of well-characterized planetary systems around thick disc stars. This system challenges theories of formation and populations of planets around thick disc stars with its Ultra-Short Period super-Earth and the wide period distribution of these two planets spanning the radius valley.
planets and satellites: interiors
planets and satellites: individual: TOI-2345 b & c
planets and satellites: detection
techniques: photometric - techniques: radial velocities
stars: individual: TOI-2345
Author
Yoshi Eschen
The University of Warwick
T.G. Wilson
The University of Warwick
A. Bonfanti
Institut fur Weltraumforschung
Carina Persson
Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics
S.G. Sousa
University of Porto
M. Lendl
University of Geneva
A. Heitzmann
University of Geneva
A.E. Simon
University of Bern
Physics Institute
G. Olofsson
Stockholm University
A. Castro-González
University of Geneva
J. A. Egger
Physics Institute
L. Fossati
Institut fur Weltraumforschung
A. J. Mustill
Lund University
H. P. Osborn
University of Bern
Swiss Federal Institute of Technology in Zürich (ETH)
Hugo G. Vivien
Laboratoire d'Astrophysique de Marseille
Y. Alibert
University of Bern
Physics Institute
R. Alonso
University of La Laguna
Instituto de Astrofísica de Canarias
T. Bárczy
Admatis
D. Barrado
European Space Agency (ESA)
S.C.C. Barros
University of Porto
W. Baumjohann
Institut fur Weltraumforschung
W. Benz
University of Bern
Physics Institute
N. Billot
University of Geneva
L. Borsato
Istituto nazionale di astrofisica (INAF)
A. Brandeker
Stockholm University
C. Broeg
Physics Institute
University of Bern
M. Buder
German Aerospace Center (DLR)
D. A. Caldwell
SETI Institute
National Aeronautics and Space Administration (NASA)
A. Collier Cameron
University of St Andrews
A. Correia
University of Coimbra
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
Physics Institute
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)
J. Farinato
Istituto nazionale di astrofisica (INAF)
A. Fortier
University of Bern
Physics Institute
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
Robert Goeke
Massachusetts Institute of Technology (MIT)
M. Gudel
University of Vienna
Maximilian N. Günther
European Space Agency (ESA)
J. Hasiba
Institut fur Weltraumforschung
Ch. Helling
Technische Universität Graz
Institut fur Weltraumforschung
K. Isaak
European Space Agency (ESA)
Jon M. Jenkins
National Aeronautics and Space Administration (NASA)
Tatiana Keller
Physics Institute
University of Bern
L. L. Kiss
Eötvös Loránd University (ELTE)
Research Centre For Astronomy and Earth Sciences
D. Kitzmann
Physics Institute
University of Bern
Judith Korth
University of Geneva
K. W.F. Lam
German Aerospace Center (DLR)
J. Laskar
Paris Observatory
A. L. des Etangs
Institut d 'Astrophysique de Paris
A. Leleu
Physics Institute
University of Geneva
D. Magrin
Istituto nazionale di astrofisica (INAF)
P. Maxted
Keele University
Bruno Merín
European Space Agency (ESA)
C. Mordasini
Physics Institute
University of Bern
Valerio Nascimbeni
Istituto nazionale di astrofisica (INAF)
R. Ottensamer
University of Vienna
I. Pagano
Istituto nazionale di astrofisica (INAF)
Enric Palle
Instituto de Astrofísica de Canarias
University of La Laguna
G. Peter
German Aerospace Center (DLR)
D. Piazza
University of Bern
Giampaolo P. Piotto
University of Padua
Istituto nazionale di astrofisica (INAF)
Don L. Pollacco
The University of Warwick
D. Queloz
University of Cambridge
Swiss Federal Institute of Technology in Zürich (ETH)
Roberto Ragazzoni
Istituto nazionale di astrofisica (INAF)
University of Padua
N. Rando
European Space Agency (ESA)
F. Ratti
European Space Agency (ESA)
H. Rauer
Freie Universität Berlin
German Aerospace Center (DLR)
I. Ribas
Centre Tecnològic de Telecomunicacions de Catalunya (CTTC)
Spanish National Research Council (CSIC)
N. C. Santos
University of Porto
Gaetano Scandariato
Istituto nazionale di astrofisica (INAF)
D. Segransan
University of Geneva
Avi Shporer
Massachusetts Institute of Technology (MIT)
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)
HUN-REN-ELTE Exoplanet Research Group
S. Udry
University of Geneva
S. Ulmer-Moll
University of Liège
Leiden University
V. Van Grootel
University of Liège
J. Venturini
University of Geneva
E. Villaver
University of La Laguna
Instituto de Astrofísica de Canarias
N. A. Walton
University of Cambridge
David Watanabe
Planetary Discoveries
S. Wolf
Physics Institute
C. Ziegler
Stephen F. Austin State University
Monthly Notices of the Royal Astronomical Society
00358711 (ISSN) 13652966 (eISSN)
Vol. 544 2 2614-2636Subject Categories (SSIF 2025)
Astronomy, Astrophysics, and Cosmology
DOI
10.1093/mnras/staf1806