Transit timing variations in HIP 41378: CHEOPS and TESS confirm a non-transiting sixth planet in the system

Leonardi, P. and Borsato, L. and Pagliaro, L. and Kubyshkina, D. and Egger, J. A. and Wilson, T. G. and Heitzmann, A. and Brandeker, A. and Günther, M. N. and Nascimbeni, V. and Leleu, A. and Bonfanti, A. and Sousa, S. G. and Mantovan, G. and Piotto, G. and Fossati, L. and Nardiello, D. and Zingales, T. and Adibekyan, V. and Pezzotti, C. and Akinsanmi, B. and Alibert, Y. and Alonso, R. and Bàrczy, T. and Barrado y Navascués, D. and Barros, S. C. C. and Baumjohann, W. and Benz, W. and Billot, N. and Broeg, C. and Buder, M. and Collier Cameron, A. and Corral Van Damme, C. and Correia, A. C. M. and Csizmadia, Sz. and Cubillos, P. E. and Davies, M. B. and Deleuil, M. and Deline, A. and Demangeon, O. D. S. and Demory, B.-O. and Derekas, A. and Edwards, B. and Ehrenreich, D. and Erikson, A. and Farinato, J. and Fortier, A. and Fridlund, M. and Gandolfi, D. and Gazeas, K. and Gillon, M. and Güdel, M. and Helling, Ch. and Isaak, K. G. and Kiss, L. L. and Korth, J. and Lam, K. W. F. and Laskar, J. and Lecavelier des Etangs, A. and Lendl, M. and Magrin, D. and Maxted, P. F. L. and Merin, B. and Mordasini, C. and Olofsson, G. and Ottensamer, R. and Pagano, I. and Palle, E. and Peter, G. and Piazza, D. and Pollacco, D. and Queloz, D. and Ragazzoni, R. and Rando, N. and Rauer, H. and Ribas, I. and Santos, N. C. and Scandariato, G. and Ségransan, D. and Simon, A. E. and Smith, A. M. S. and Stalport, M. and Sulis, S. and Szabó, Gy. M. and Udry, S. and Ulmer, B and Ulmer-Moll, S. and Van Grootel, V. and Venturini, J. and Villaver, E. and Walton, N. A. and Wolf, S. (2025) Transit timing variations in HIP 41378: CHEOPS and TESS confirm a non-transiting sixth planet in the system. Astronomy and Astrophysics, 702, A211. EDP Sciences. doi: 10.1051/0004-6361/202555253. ISSN 0004-6361.

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Official URL: https://www.aanda.org/articles/aa/full_html/2025/10/aa55253-25/aa55253-25.html

Abstract

In multiple-planet systems, gravitational interactions of exoplanets could lead to transit timing variations (TTVs), whose amplitude becomes significantly enhanced when planets are in or near mean-motion resonances (MMRs), making them more easily detectable. In cases where both TTVs and radial velocity (RV) measurements are available, combined analysis can break degeneracies and provide robust planetary and system characterization, even detecting non-transiting planets. In this context, HIP 41378 hosts five confirmed transiting planets with periods ranging from 15 to over 542 days, providing a unique dynamical laboratory for investigating wide multi-planet systems analogous to the Solar System. In this study, we present an intensive space-based photometric follow-up of HIP 41378, combining 15 new CHEOPS observations with eight TESS sectors, alongside data from K2, Spitzer, HST, and 311 HARPS spectra. We dynamically modeled the TTVs and RV signals of the two inner sub-Neptunes via N-body integration. These planets, HIP 41378 b (Pb = 15.57 days, Rb = 2.45 R⊕) and HIP 41378 c (Pc = 31.71 days, Rc = 2.57 R⊕), are close to (∆ ~ 1.8%) a 2:1 period commensurability. We report a clear detection of TTVs with amplitudes of 20 minutes for planet b and greater than 3 hours for planet c. We dynamically confirm the planetary nature of HIP 41378 g, a non-transiting planet with a period of about 64 days and a mass of about 7 M⊕, close to a 2:1 commensurability with planet c, suggesting a possible mean-motion resonance chain in the inner system. Our precise determination of the masses, eccentricities, and radii of HIP 41378 b and c enabled us to investigate their possible volatile-rich compositions. Finally, by leveraging on the last TESS sectors we constrained the period of HIP 41378 d to three possible aliases (Pd = 278, 371, and 1113 days) suggesting that the system could be placed in a double quasi resonant chain, highlighting its complex dynamical architecture.

Item URL in elib:

https://elib.dlr.de/220667/

Document Type:

Article

Title:

Transit timing variations in HIP 41378: CHEOPS and TESS confirm a non-transiting sixth planet in the system

Authors:

Authors	Institution or Email of Authors	Author's ORCID iD	ORCID Put Code
Leonardi, P.	Dipartimento di Fisica e Astronomia 'Galileo Galilei', Università degli Studi di Padova, Vicolo dell'Osservatorio 3, I-35122 Padova, Italy; Dipartimento di Fisica, Università di Trento, Via Sommarive 14, 38123, Povo, Trento, Italy	UNSPECIFIED	UNSPECIFIED
Borsato, L.	Dipartimento di Fisica e Astronomia, Universita degli Studi di Padova, via Marzolo 8, 35131 Padova, Italy	UNSPECIFIED	UNSPECIFIED
Pagliaro, L.	Dipartimento di Fisica e Astronomia, Università degli Studi di Padova, Vicolo dell'Osservatorio 3, 35122, Padova, Italy	UNSPECIFIED	UNSPECIFIED
Kubyshkina, D.	Space Research Institute, Austrian Academy of Sciences, Graz, Austria	UNSPECIFIED	UNSPECIFIED
Egger, J. A.	Physikalisches Institut, University of Bern, Gesellschaftsstrasse 6, 3012, Bern, Switzerland	UNSPECIFIED	UNSPECIFIED
Wilson, T. G.	Department of Physics, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL, UK	UNSPECIFIED	UNSPECIFIED
Heitzmann, A.	Observatoire Astronomique de l'Université de Genève, Chemin Pegasi 51, 1290, Versoix, Switzerland	UNSPECIFIED	UNSPECIFIED
Brandeker, A.	Department of Astronomy , Stockholm University, SE-106 91 Stockholm, Sweden	UNSPECIFIED	UNSPECIFIED
Günther, M. N.	European Space Agency (ESA), European Space Research and Technology Centre (ESTEC), Keplerlaan 1, 2201 AZ, Noordwijk, The Netherlands	UNSPECIFIED	UNSPECIFIED
Nascimbeni, V.	INAF, Osservatorio Astrofisico di Catania, Via S. Sofia 78, I-95123 Catania, Italy	UNSPECIFIED	UNSPECIFIED
Leleu, A.	Observatoire Astronomique de l’Université de Genève, CheminPegasi 51, Versoix, Switzerland	UNSPECIFIED	UNSPECIFIED
Bonfanti, A.	Space Research Institute, Austrian Academy of Sciences, Austria	UNSPECIFIED	UNSPECIFIED
Sousa, S. G.	Instituto de Astrofísica e Ciências do Espaço, Universidade do Porto, CAUP, Rua das Estrelas, 4150-762, Porto, Portugal	UNSPECIFIED	UNSPECIFIED
Mantovan, G.	Dipartimento di Fisica e Astronomia 'Galileo Galilei', Università degli Studi di Padova, Vicolo dell'Osservatorio 3, I-35122 Padova, Italy; INAF, Osservatorio Astronomico di Padova, Vicolo dell'Osservatorio 5, I-35122 Padova, Italy	UNSPECIFIED	UNSPECIFIED
Piotto, G.	INAF – Osservatorio Astronomico di Padova, vicolo dell Osservatorio 5, 35122 Padova, Italy	UNSPECIFIED	UNSPECIFIED
Fossati, L.	Space Research Institute, Austrian Academy of Sciences, Schmiedlstrasse 6, A-8042 Graz, Austria	https://orcid.org/0000-0003-4426-9530	UNSPECIFIED
Nardiello, D.	Dipartimento di Fisica e Astronomia, ’G. Galilei’, Universita degli Studi di Padova, Padova, Italy	UNSPECIFIED	UNSPECIFIED
Zingales, T.	Dipartimento di Fisica e Astronomia "Galileo Galilei", Universita degli Studi di Padova, Vicolo dell'Osservatorio 3, 35122, Padova, Italy; INAF, Osservatorio Astronomico di Padova, Vicolo dell'Osservatorio 5, 35122, Padova, Italy	UNSPECIFIED	UNSPECIFIED
Adibekyan, V.	Instituto de Astrofisica e Ciencias do Espaco, Universidade do Porto, CAUP, Rua das Estrelas, 4150-762 Porto, Portugal	UNSPECIFIED	UNSPECIFIED
Pezzotti, C.	Space sciences, Technologies and Astrophysics Research (STAR) Institute, Université de Liège, Allée du 6 Août 19C, 4000, Liège, Belgium	UNSPECIFIED	UNSPECIFIED
Akinsanmi, B.	Observatoire astronomique de l'Université de Genève, chemin Pegasi 51, 1290, Versoix, Switzerland	UNSPECIFIED	UNSPECIFIED
Alibert, Y.	Physikalisches Institut, University of Bern	UNSPECIFIED	UNSPECIFIED
Alonso, R.	Instituto de Astrofisica de Canarias (IAC), 38205, La Laguna, Tenerife, Spain; Departamento de Astrofisica, Universidad de La Laguna, 38206, La Laguna, Tenerife, Spain	UNSPECIFIED	UNSPECIFIED
Bàrczy, T.	Admatis, Miskolc, Hungary	UNSPECIFIED	UNSPECIFIED
Barrado y Navascués, D.	Depto. de Astrofisica, Centro de Astrobiologia (CSIC-INTA), ESAC campus, 28692, Villanueva de la Cañada, Madrid, Spain	UNSPECIFIED	UNSPECIFIED
Barros, S. C. C.	Instituto de Astrofisica e Ciencias do Espaco, Universidade do Porto, CAUP, Rua das Estrelas, 4150-762 Porto, Portugal	UNSPECIFIED	UNSPECIFIED
Baumjohann, W.	Space Research Institute, Austrian Academy of Sciences, Austria	UNSPECIFIED	UNSPECIFIED
Benz, W.	Physikalisches Institut,University of Bern, Sidlerstraße 5, CH-3012 Bern, Switzerland	UNSPECIFIED	UNSPECIFIED
Billot, N.	Observatoire de Genève, University of Geneva, Switzerland	UNSPECIFIED	UNSPECIFIED
Broeg, C.	Physikalisches Institut, University of Bern, Bern, Switzerland	UNSPECIFIED	UNSPECIFIED
Buder, M.	Maximilian.Buder (at) dlr.de	https://orcid.org/0009-0006-9440-236X	199243788
Collier Cameron, A.	SUPA, School of Physics and Astronomy, University of St. Andrews	UNSPECIFIED	UNSPECIFIED
Corral Van Damme, C.	ESA/ESTEC, Niederlande	UNSPECIFIED	UNSPECIFIED
Correia, A. C. M.	CFisUC, Department of Physics, University of Coimbra, 3004-516 Coimbra, Portugal	UNSPECIFIED	UNSPECIFIED
Csizmadia, Sz.	szilard.csizmadia (at) dlr.de	https://orcid.org/0000-0001-6803-9698	UNSPECIFIED
Cubillos, P. E.	INAF, Osservatorio Astrofisico di Torino, Via Osservatorio, 20, 10025, Pino Torinese, To, Italy; Space Research Institute, Austrian Academy of Sciences, Schmiedlstrasse 6, 8042, Graz, Austria	UNSPECIFIED	UNSPECIFIED
Davies, M. B.	Lund Observatory, Department of Astronomy and Theoretical Physics, Lund University, 22100, Lund, Sweden	UNSPECIFIED	UNSPECIFIED
Deleuil, M.	Aix Marseille Universite, CNRS, LAM (Laboratoire d Astrophysique de Marseille) UMR 7326, 13388, Marseille, France	UNSPECIFIED	UNSPECIFIED
Deline, A.	Observatoire de Genève, University of Geneva, Switzerland	UNSPECIFIED	UNSPECIFIED
Demangeon, O. D. S.	Instituto de Astrofísica e Ciências do Espaço, Universidade do Porto, CAUP, Rua das Estrelas, 4150-762, Porto, Portugal	UNSPECIFIED	UNSPECIFIED
Demory, B.-O.	Center for Space and Habitability, Gesellsschaftstrasse 6, 3012, Bern, Switzerland	UNSPECIFIED	UNSPECIFIED
Derekas, A.	ELTE Eötvös Loránd University, Gothard Astrophysical Observatory, Szent Imre h. u. 112, 9700 Szombathely, Hungary	UNSPECIFIED	UNSPECIFIED
Edwards, B.	SRON Netherlands Institute for Space Research, Niels Bohrweg 4, 2333 CA, Leiden, The Netherlands	UNSPECIFIED	UNSPECIFIED
Ehrenreich, D.	Observatoire de Genève, University of Geneva, Switzerland	UNSPECIFIED	UNSPECIFIED
Erikson, A.	anders.erikson (at) dlr.de	UNSPECIFIED	UNSPECIFIED
Farinato, J.	INAF - Osservatorio Astronomico di Padova, Vicolo dell'Osservatorio 5, 35122 Padova, Italy	UNSPECIFIED	UNSPECIFIED
Fortier, A.	Physikalisches Institut, University of Bern, Bern, Switzerland	UNSPECIFIED	UNSPECIFIED
Fridlund, M.	Department of Space, Earth and Environment, Chalmers University of Technology, Onsala Space Observatory, 439 92, Onsala, Sweden; Leiden Observatory, Leiden University, 2333CA, Leiden, The Netherlands	UNSPECIFIED	UNSPECIFIED
Gandolfi, D.	Dipartimento di Fisica, Università di Torino, via P. Giuria 1, I-10125 Torino, Italy	UNSPECIFIED	UNSPECIFIED
Gazeas, K.	National and Kapodistrian University of Athens, Department of Physics, University Campus, Zografos 157 84, Athens, Greece	UNSPECIFIED	UNSPECIFIED
Gillon, M.	Institut d'Astrophysique et de Géophysique, Universitée de Liège, Allée du 6 août 17, B-4000 Liège, Belgium	UNSPECIFIED	UNSPECIFIED
Güdel, M.	Department of Astrophysics, University of Vienna, Türkenschanzstraße 17, 1180, Vienna, Austria	UNSPECIFIED	UNSPECIFIED
Helling, Ch.	Space Research Institute, Austrian Academy of Sciences, Graz, Austria	UNSPECIFIED	UNSPECIFIED
Isaak, K. G.	Science and Operations Department - Science Division (SCI-SC), Directorate of Science, European Space Agency (ESA), European Space Research and Technology Centre (ESTEC), Keplerlaan 1, 2201-AZ, Noordwijk, The Netherlands	UNSPECIFIED	UNSPECIFIED
Kiss, L. L.	Konkoly Observatory, Research Centre for Astronomy and Earth, Budapest, Hungary	UNSPECIFIED	UNSPECIFIED
Korth, J.	Lund Observatory, Division of Astrophysics, Department of Physics, Lund University, Lund, Sweden	UNSPECIFIED	UNSPECIFIED
Lam, K. W. F.	DLR, Institute of Planetary Research, Dept. of Extrasolar Planets and Atmospheres, Berlin, D-12489, Rutherfordstrasse 2.	UNSPECIFIED	UNSPECIFIED
Laskar, J.	IMCCE, UMR8028 CNRS, Observatoire de Paris, PSL Univ.,Sorbonne Univ., 77 av. Denfert-Rochereau, 75014 Paris, France	UNSPECIFIED	UNSPECIFIED
Lecavelier des Etangs, A.	Institut d Astrophysique de Paris, CNRS, UMR 7095 & Sorbonne Universites, UPMC Paris 6, 98 bis bd Arago, 75014 Paris, France	UNSPECIFIED	UNSPECIFIED
Lendl, M.	Observatoire de Genève, Université de Genève, Chemin Pegasi, 51, 1290, Versoix, Switzerland	UNSPECIFIED	UNSPECIFIED
Magrin, D.	Dipartimento di Fisica e Astronomia, Universita degli Studi di Padova, Vicolo dell Osservatorio 3, 35122 Padova, Italy	UNSPECIFIED	UNSPECIFIED
Maxted, P. F. L.	Astrophysics Group, Keele University, Staffordshire	UNSPECIFIED	UNSPECIFIED
Merin, B.	European Space Agency, ESA – European Space Astronomy Centre, Camino Bajo del Castillo s/n, 28692, Villanueva de la Cañada, Madrid, Spain	UNSPECIFIED	UNSPECIFIED
Mordasini, C.	Physikalisches Institut, University of Bern, Gesellschaftsstrasse 6, 3012, Bern, Switzerland	UNSPECIFIED	UNSPECIFIED
Olofsson, G.	Department of Astronomy, Stockholm University, AlbaNova University Center, 10691 Stockholm, Sweden	UNSPECIFIED	UNSPECIFIED
Ottensamer, R.	Dept. of Astrophysics, University of Vienna, Austria	UNSPECIFIED	UNSPECIFIED
Pagano, I.	INAF – Osservatorio Astrofisico di Catania, via S. Sofia 78, 95123 Catania, Italy	UNSPECIFIED	UNSPECIFIED
Palle, E.	Instituto de Astrofísica de Canarias (IAC), 38205 La Laguna, Tenerife, Spain; Departamento de Astrofísica, Universidad de La Laguna (ULL), 38206 La Laguna, Tenerife, Spain	UNSPECIFIED	UNSPECIFIED
Peter, G.	Gisbert.Peter (at) dlr.de	https://orcid.org/0000-0001-6101-2513	UNSPECIFIED
Piazza, D.	Physikalisches Institut,University of Bern, Sidlerstraße 5, CH-3012 Bern, Switzerland	UNSPECIFIED	UNSPECIFIED
Pollacco, D.	Department of Physics, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL, UK; Centre for Exoplanets and Habitability, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL, UK	UNSPECIFIED	UNSPECIFIED
Queloz, D.	ETH Zurich, Department of Physics, Wolfgang-Pauli-Strasse 2, 8093, Zurich, Switzerland; Cavendish Laboratory, JJ Thomson Avenue, Cambridge, CB3 0HE, UK	UNSPECIFIED	UNSPECIFIED
Ragazzoni, R.	Dipartimento di Fisica e Astronomia, Universita degli Studi di Padova, Vicolo dell Osservatorio 3, 35122 Padova, Italy	UNSPECIFIED	UNSPECIFIED
Rando, N.	ESA/ESTEC, Noordwijk, Niederlande	UNSPECIFIED	UNSPECIFIED
Rauer, H.	heike.rauer (at) dlr.de	UNSPECIFIED	UNSPECIFIED
Ribas, I.	Institut de Ciències de l’Espai (CSIC), Campus UAB, c/ de Can Magrans s/n, Barcelona, Spain; Institut d’Estudis Espacials de Catalunya, Barcelona, Spain	UNSPECIFIED	UNSPECIFIED
Santos, N. C.	Instituto de Astrofisica e Ciencias do Espaco, Universidade do Porto, CAUP, Rua das Estrelas, 4150-762 Porto, Portugal; Departamento de Fisica e Astronomia, Faculdade de Ciencias, Universidade do Porto, Rua Campo Alegre, 4169-007 Porto, Portugal	UNSPECIFIED	UNSPECIFIED
Scandariato, G.	INAF, Osservatorio Astrofisico di Catania, Via S. Sofia 78, I-95123 Catania, Italy	UNSPECIFIED	UNSPECIFIED
Ségransan, D.	Geneva Observatory, University of Geneva, Chemin Pegasi 51, CH-1290 Versoix, Switzerland	UNSPECIFIED	UNSPECIFIED
Simon, A. E.	Center for Space and Habitability, University of Bern, Switzerland	UNSPECIFIED	UNSPECIFIED
Smith, A. M. S.	alexis.smith (at) dlr.de	https://orcid.org/0000-0002-2386-4341	UNSPECIFIED
Stalport, M.	Astrobiology Research Unit, Université de Liège, Allée du 6 Août 19C, B-4000 Liège, Belgium; Space Sciences, Technologies and Astrophysics Research (STAR) Institute, Université de Liège, Allée du 6 Août 19C, B-4000 Liège, Belgium	UNSPECIFIED	UNSPECIFIED
Sulis, S.	Aix Marseille Univ., CNRS, CNES, LAM, 38 Rue Frédéric Joliot-Curie, 13388, Marseille, France	UNSPECIFIED	UNSPECIFIED
Szabó, Gy. M.	ELTE Eötvös Loránd University, Gothard Astrophysical Observatory, 9700, Szombathely, Szent Imre h. u. 112, Hungary ; MTA-ELTE Exoplanet Research Group, 9700, Szombathely, Szent Imre h. u. 112, Hungary	UNSPECIFIED	UNSPECIFIED
Udry, S.	Geneva Observatory, University of Geneva, Chemin Pegasi 51, CH-1290 Versoix, Switzerland	UNSPECIFIED	UNSPECIFIED
Ulmer, B	bernd.ulmer (at) dlr.de	UNSPECIFIED	UNSPECIFIED
Ulmer-Moll, S.	Observatoire de Genève, Université de Genève, Chemin Pegasi, 51, 1290, Versoix, Switzerland	UNSPECIFIED	UNSPECIFIED
Van Grootel, V.	Space sciences, Technologies and Astrophysics Research (STAR) Institute, Université de Liège, Allée du 6 Août 19C, 4000 Liège, Belgium	UNSPECIFIED	UNSPECIFIED
Venturini, J.	Observatoire Astronomique de l'Université de Genève, Chemin Pegasi 51, 1290, Versoix, Switzerland	UNSPECIFIED	UNSPECIFIED
Villaver, E.	Instituto de Astrofisica de Canarias, Via Lactea s/n, 38200, La Laguna, Tenerife, Spain; Departamento de Astrofisica, Universidad de La Laguna, Astrofísico Francisco Sanchez s/n, 38206, La Laguna, Tenerife, Spain	UNSPECIFIED	UNSPECIFIED
Walton, N. A.	Institute of Astronomy, University of Cambridge, Cambridge, UK	UNSPECIFIED	UNSPECIFIED
Wolf, S.	Observatoire Astronomique de l'Université de Genève, Chemin Pegasi 51, CH-1290 Versoix, Switzerland	UNSPECIFIED	UNSPECIFIED

Date:

2025

Journal or Publication Title:

Astronomy and Astrophysics

Refereed publication:

Yes

Open Access:

Yes

Gold Open Access:

Yes

In SCOPUS:

Yes

In ISI Web of Science:

Yes

Volume:

702

DOI:

10.1051/0004-6361/202555253

Page Range:

A211

Publisher:

EDP Sciences

ISSN:

0004-6361

Status:

Published

Keywords:

methods: data analysis, techniques: photometric, planets and satellites: detection, planets and satellites: dynamical evolution and stability, stars: individual: HIP 41378, Earth and Planetary Astrophysics

HGF - Research field:

Aeronautics, Space and Transport

HGF - Program:

Space

HGF - Program Themes:

Space Exploration

DLR - Research area:

Raumfahrt

DLR - Program:

R EW - Space Exploration

DLR - Research theme (Project):

R - CHEOPS Science, R - Project CHEOPS

Location:

Berlin-Adlershof , Köln-Porz

Institutes and Institutions:

Institute of Planetary Research > Extrasolar Planets and Atmospheres
Institute of Optical Sensor Systems > Space Instruments
Division of the Chair of the Executive Board

Deposited By:

Smith, Dr Alexis M S

Deposited On:

10 Dec 2025 09:46

Last Modified:

24 Dec 2025 04:06

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