An ultra-short period super-Earth and sub-Neptune spanning the Radius Valley orbiting the kinematic thick disc star TOI-2345

Yoshi Nike Emilia Eschen; Thomas G. Wilson; Andrea Bonfanti; Carina M. Persson; Sérgio G. Sousa; Monika Lendl; Alexis Heitzmann; Attila E. Simon; Göran Olofsson; Amadeo Castro-González; Jo Ann Egger; Luca Fossati; Alexander James Mustill; Hugh P. Osborn; Hugo G. Vivien; Yann Alibert; Roi Alonso; Tamas Bárczy; David Barrado; Susana C.C. Barros; Wolfgang Baumjohann; Willy Benz; Nicolas Billot; Luca Borsato; Alexis Brandeker; Christopher Broeg; Maximilian Buder; Douglas A. Caldwell; Andrew Collier Cameron; Alexandre C.M. Correia; Szilard Csizmadia; Patricio E. Cubillos; Melvyn B. Davies; Magali Deleuil; Adrien Deline; Olivier D.S. Demangeon; Brice Olivier Demory; Aliz Derekas; Billy Edwards; David Ehrenreich; Anders Erikson; Jacopo Farinato; Andrea Fortier; Malcolm Fridlund; Davide Gandolfi; Kosmas Gazeas; Michaël Gillon; Robert Goeke; Manuel Güdel; Maximilian N. Günther; Johann Hasiba; Ch Helling; Kate G. Isaak; Jon M. Jenkins; Tatiana Keller; Laszlo L. Kiss; Daniel Kitzmann; Judith Korth; Kristine W.F. Lam; Jacques Laskar; Alain Lecavelier Des Etangs; Adrien Leleu; Demetrio Magrin; Pierre F.L. Maxted; Bruno Merín; Christoph Mordasini; Valerio Nascimbeni; Roland Ottensamer; Isabella Pagano; Enric Pallé; Gisbert Peter; Daniele Piazza; Giampaolo Piotto; Don Pollacco; Didier Queloz; Roberto Ragazzoni; Nicola Rando; Francesco Ratti; Heike Rauer; Ignasi Ribas; Nuno C. Santos; Gaetano Scandariato; Damien Ségransan; Avi Shporer; Alexis M.S. Smith; Manu Stalport; Sophia Sulis; Gyula M. Szabó; Stéphane Udry; Solène Ulmer-Moll; Valérie Van Grootel; Julia Venturini; Eva Villaver; Nicholas A. Walton; David Watanabe; Sebastian Wolf; Carl Ziegler

doi:10.1093/mnras/staf1806

An ultra-short period super-Earth and sub-Neptune spanning the Radius Valley orbiting the kinematic thick disc star TOI-2345

Yoshi Nike Emilia Eschen, Thomas G. Wilson, Andrea Bonfanti, Carina M. Persson, Sérgio G. Sousa, Monika Lendl, Alexis Heitzmann, Attila E. Simon, Göran Olofsson, Amadeo Castro-González, Jo Ann Egger, Luca Fossati, Alexander James Mustill, Hugh P. Osborn, Hugo G. Vivien, Yann Alibert, Roi Alonso, Tamas Bárczy, David Barrado, Susana C.C. BarrosWolfgang Baumjohann, Willy Benz, Nicolas Billot, Luca Borsato, Alexis Brandeker, Christopher Broeg, Maximilian Buder, Douglas A. Caldwell, Andrew Collier Cameron, Alexandre C.M. Correia, Szilard Csizmadia, Patricio E. Cubillos, Melvyn B. Davies, Magali Deleuil, Adrien Deline, Olivier D.S. Demangeon, Brice Olivier Demory, Aliz Derekas, Billy Edwards, David Ehrenreich, Anders Erikson, Jacopo Farinato, Andrea Fortier, Malcolm Fridlund, Davide Gandolfi, Kosmas Gazeas, Michaël Gillon, Robert Goeke, Manuel Güdel, Maximilian N. Günther, Johann Hasiba, Ch Helling, Kate G. Isaak, Jon M. Jenkins, Tatiana Keller, Laszlo L. Kiss, Daniel Kitzmann, Judith Korth, Kristine W.F. Lam, Jacques Laskar, Alain Lecavelier Des Etangs, Adrien Leleu, Demetrio Magrin, Pierre F.L. Maxted, Bruno Merín, Christoph Mordasini, Valerio Nascimbeni, Roland Ottensamer, Isabella Pagano, Enric Pallé, Gisbert Peter, Daniele Piazza, Giampaolo Piotto, Don Pollacco, Didier Queloz, Roberto Ragazzoni, Nicola Rando, Francesco Ratti, Heike Rauer, Ignasi Ribas, Nuno C. Santos, Gaetano Scandariato, Damien Ségransan, Avi Shporer, Alexis M.S. Smith, Manu Stalport, Sophia Sulis, Gyula M. Szabó, Stéphane Udry, Solène Ulmer-Moll, Valérie Van Grootel, Julia Venturini, Eva Villaver, Nicholas A. Walton, David Watanabe, Sebastian Wolf, Carl Ziegler

Research output: Contribution to journal › Article › peer-review

Abstract

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.

Original language	English
Pages (from-to)	2614-2636
Number of pages	23
Journal	Monthly Notices of the Royal Astronomical Society
Volume	544
Issue number	2
DOIs	https://doi.org/10.1093/mnras/staf1806
Publication status	Published - 1 Dec 2025
Externally published	Yes

Keywords

planets and satellites: detection
planets and satellites: individual: TOI-2345 b & c
planets and satellites: interiors
stars: individual: TOI-2345
techniques: photometric - techniques: radial velocities

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10.1093/mnras/staf1806

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Eschen, Y. N. E., Wilson, T. G., Bonfanti, A., Persson, C. M., Sousa, S. G., Lendl, M., Heitzmann, A., Simon, A. E., Olofsson, G., Castro-González, A., Egger, J. A., Fossati, L., Mustill, A. J., Osborn, H. P., Vivien, H. G., Alibert, Y., Alonso, R., Bárczy, T., Barrado, D., ... Ziegler, C. (2025). An ultra-short period super-Earth and sub-Neptune spanning the Radius Valley orbiting the kinematic thick disc star TOI-2345. Monthly Notices of the Royal Astronomical Society, 544(2), 2614-2636. https://doi.org/10.1093/mnras/staf1806

@article{f7bf0633c84f4738849cd045e60a84f3,

title = "An ultra-short period super-Earth and sub-Neptune spanning the Radius Valley orbiting the kinematic thick disc star TOI-2345",

abstract = "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.",

keywords = "planets and satellites: detection, planets and satellites: individual: TOI-2345 b \& c, planets and satellites: interiors, stars: individual: TOI-2345, techniques: photometric - techniques: radial velocities",

author = "Eschen, \{Yoshi Nike Emilia\} and Wilson, \{Thomas G.\} and Andrea Bonfanti and Persson, \{Carina M.\} and Sousa, \{S{\'e}rgio G.\} and Monika Lendl and Alexis Heitzmann and Simon, \{Attila E.\} and G{\"o}ran Olofsson and Amadeo Castro-Gonz{\'a}lez and Egger, \{Jo Ann\} and Luca Fossati and Mustill, \{Alexander James\} and Osborn, \{Hugh P.\} and Vivien, \{Hugo G.\} and Yann Alibert and Roi Alonso and Tamas B{\'a}rczy and David Barrado and Barros, \{Susana C.C.\} and Wolfgang Baumjohann and Willy Benz and Nicolas Billot and Luca Borsato and Alexis Brandeker and Christopher Broeg and Maximilian Buder and Caldwell, \{Douglas A.\} and Cameron, \{Andrew Collier\} and Correia, \{Alexandre C.M.\} and Szilard Csizmadia and Cubillos, \{Patricio E.\} and Davies, \{Melvyn B.\} and Magali Deleuil and Adrien Deline and Demangeon, \{Olivier D.S.\} and Demory, \{Brice Olivier\} and Aliz Derekas and Billy Edwards and David Ehrenreich and Anders Erikson and Jacopo Farinato and Andrea Fortier and Malcolm Fridlund and Davide Gandolfi and Kosmas Gazeas and Micha{\"e}l Gillon and Robert Goeke and Manuel G{\"u}del and G{\"u}nther, \{Maximilian N.\} and Johann Hasiba and Ch Helling and Isaak, \{Kate G.\} and Jenkins, \{Jon M.\} and Tatiana Keller and Kiss, \{Laszlo L.\} and Daniel Kitzmann and Judith Korth and Lam, \{Kristine W.F.\} and Jacques Laskar and \{Des Etangs\}, \{Alain Lecavelier\} and Adrien Leleu and Demetrio Magrin and Maxted, \{Pierre F.L.\} and Bruno Mer{\'i}n and Christoph Mordasini and Valerio Nascimbeni and Roland Ottensamer and Isabella Pagano and Enric Pall{\'e} and Gisbert Peter and Daniele Piazza and Giampaolo Piotto and Don Pollacco and Didier Queloz and Roberto Ragazzoni and Nicola Rando and Francesco Ratti and Heike Rauer and Ignasi Ribas and Santos, \{Nuno C.\} and Gaetano Scandariato and Damien S{\'e}gransan and Avi Shporer and Smith, \{Alexis M.S.\} and Manu Stalport and Sophia Sulis and Szab{\'o}, \{Gyula M.\} and St{\'e}phane Udry and Sol{\`e}ne Ulmer-Moll and \{Van Grootel\}, Val{\'e}rie and Julia Venturini and Eva Villaver and Walton, \{Nicholas A.\} and David Watanabe and Sebastian Wolf and Carl Ziegler",

note = "Publisher Copyright: {\textcopyright} 2025 The Author(s). Published by Oxford University Press on behalf of Royal Astronomical Society.",

year = "2025",

month = dec,

day = "1",

doi = "10.1093/mnras/staf1806",

language = "English",

volume = "544",

pages = "2614--2636",

journal = "Monthly Notices of the Royal Astronomical Society",

issn = "0035-8711",

number = "2",

}

Eschen, YNE, Wilson, TG, Bonfanti, A, Persson, CM, Sousa, SG, Lendl, M, Heitzmann, A, Simon, AE, Olofsson, G, Castro-González, A, Egger, JA, Fossati, L, Mustill, AJ, Osborn, HP, Vivien, HG, Alibert, Y, Alonso, R, Bárczy, T, Barrado, D, Barros, SCC, Baumjohann, W, Benz, W, Billot, N, Borsato, L, Brandeker, A, Broeg, C, Buder, M, Caldwell, DA, Cameron, AC, Correia, ACM, Csizmadia, S, Cubillos, PE, Davies, MB, Deleuil, M, Deline, A, Demangeon, ODS, Demory, BO, Derekas, A, Edwards, B, Ehrenreich, D, Erikson, A, Farinato, J, Fortier, A, Fridlund, M, Gandolfi, D, Gazeas, K, Gillon, M, Goeke, R, Güdel, M, Günther, MN, Hasiba, J, Helling, C, Isaak, KG, Jenkins, JM, Keller, T, Kiss, LL, Kitzmann, D, Korth, J, Lam, KWF, Laskar, J, Des Etangs, AL, Leleu, A, Magrin, D, Maxted, PFL, Merín, B, Mordasini, C, Nascimbeni, V, Ottensamer, R, Pagano, I, Pallé, E, Peter, G, Piazza, D, Piotto, G, Pollacco, D, Queloz, D, Ragazzoni, R, Rando, N, Ratti, F, Rauer, H, Ribas, I, Santos, NC, Scandariato, G, Ségransan, D, Shporer, A, Smith, AMS, Stalport, M, Sulis, S, Szabó, GM, Udry, S, Ulmer-Moll, S, Van Grootel, V, Venturini, J, Villaver, E, Walton, NA, Watanabe, D, Wolf, S & Ziegler, C 2025, 'An ultra-short period super-Earth and sub-Neptune spanning the Radius Valley orbiting the kinematic thick disc star TOI-2345', Monthly Notices of the Royal Astronomical Society, vol. 544, no. 2, pp. 2614-2636. https://doi.org/10.1093/mnras/staf1806

TY - JOUR

T1 - An ultra-short period super-Earth and sub-Neptune spanning the Radius Valley orbiting the kinematic thick disc star TOI-2345

AU - Eschen, Yoshi Nike Emilia

AU - Wilson, Thomas G.

AU - Bonfanti, Andrea

AU - Persson, Carina M.

AU - Sousa, Sérgio G.

AU - Lendl, Monika

AU - Heitzmann, Alexis

AU - Simon, Attila E.

AU - Olofsson, Göran

AU - Castro-González, Amadeo

AU - Egger, Jo Ann

AU - Fossati, Luca

AU - Mustill, Alexander James

AU - Osborn, Hugh P.

AU - Vivien, Hugo G.

AU - Alibert, Yann

AU - Alonso, Roi

AU - Bárczy, Tamas

AU - Barrado, David

AU - Barros, Susana C.C.

AU - Baumjohann, Wolfgang

AU - Benz, Willy

AU - Billot, Nicolas

AU - Borsato, Luca

AU - Brandeker, Alexis

AU - Broeg, Christopher

AU - Buder, Maximilian

AU - Caldwell, Douglas A.

AU - Cameron, Andrew Collier

AU - Correia, Alexandre C.M.

AU - Csizmadia, Szilard

AU - Cubillos, Patricio E.

AU - Davies, Melvyn B.

AU - Deleuil, Magali

AU - Deline, Adrien

AU - Demangeon, Olivier D.S.

AU - Demory, Brice Olivier

AU - Derekas, Aliz

AU - Edwards, Billy

AU - Ehrenreich, David

AU - Erikson, Anders

AU - Farinato, Jacopo

AU - Fortier, Andrea

AU - Fridlund, Malcolm

AU - Gandolfi, Davide

AU - Gazeas, Kosmas

AU - Gillon, Michaël

AU - Goeke, Robert

AU - Güdel, Manuel

AU - Günther, Maximilian N.

AU - Hasiba, Johann

AU - Helling, Ch

AU - Isaak, Kate G.

AU - Jenkins, Jon M.

AU - Keller, Tatiana

AU - Kiss, Laszlo L.

AU - Kitzmann, Daniel

AU - Korth, Judith

AU - Lam, Kristine W.F.

AU - Laskar, Jacques

AU - Des Etangs, Alain Lecavelier

AU - Leleu, Adrien

AU - Magrin, Demetrio

AU - Maxted, Pierre F.L.

AU - Merín, Bruno

AU - Mordasini, Christoph

AU - Nascimbeni, Valerio

AU - Ottensamer, Roland

AU - Pagano, Isabella

AU - Pallé, Enric

AU - Peter, Gisbert

AU - Piazza, Daniele

AU - Piotto, Giampaolo

AU - Pollacco, Don

AU - Queloz, Didier

AU - Ragazzoni, Roberto

AU - Rando, Nicola

AU - Ratti, Francesco

AU - Rauer, Heike

AU - Ribas, Ignasi

AU - Santos, Nuno C.

AU - Scandariato, Gaetano

AU - Ségransan, Damien

AU - Shporer, Avi

AU - Smith, Alexis M.S.

AU - Stalport, Manu

AU - Sulis, Sophia

AU - Szabó, Gyula M.

AU - Udry, Stéphane

AU - Ulmer-Moll, Solène

AU - Van Grootel, Valérie

AU - Venturini, Julia

AU - Villaver, Eva

AU - Walton, Nicholas A.

AU - Watanabe, David

AU - Wolf, Sebastian

AU - Ziegler, Carl

PY - 2025/12/1

Y1 - 2025/12/1

N2 - 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.

AB - 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.

KW - planets and satellites: detection

KW - planets and satellites: individual: TOI-2345 b & c

KW - planets and satellites: interiors

KW - stars: individual: TOI-2345

KW - techniques: photometric - techniques: radial velocities

UR - https://www.scopus.com/pages/publications/105022498415

U2 - 10.1093/mnras/staf1806

DO - 10.1093/mnras/staf1806

M3 - Article

AN - SCOPUS:105022498415

SN - 0035-8711

VL - 544

SP - 2614

EP - 2636

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

IS - 2

ER -

An ultra-short period super-Earth and sub-Neptune spanning the Radius Valley orbiting the kinematic thick disc star TOI-2345

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Keywords

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