The CHEOPS view of HD 95338b: Refined transit parameters, and a search for exomoons

Kálmán, Sz. and Simon, A. E. and Deline, A. and Csizmadia, Sz. and Szabó, Gy. M. and Ehrenreich, D. and Wilson, T. G. and Günther, M. N. and Heitzmann, A. and Sousa, S. G. and Farnir, M. and Bonfanti, A. and Smith, A. M. S. and Pal, A. and Scandariato, G. and Adibekyan, V. and Brandeker, A. and Charnoz, S. and Akinsanmi, B. and Barros, S. C. C. and Song, X. and Alibert, Y. and Alonso, R. and Bàrczy, T. and Navascues, D. Barrado and Baumjohann, W. and Benz, W. and Billot, N. and Biondi, F. and Borsato, L. and Broeg, C. and Collier Cameron, A. and Corral Van Damme, C. and Correia, A. C. M. and Cubillos, P. E. and Davies, M. B. and Deleuil, M. and Demangeon, O. D. S. and Demory, B.-O. and Derekas, A. and Edwards, B. and Egger, J. A. and Erikson, A. and Fortier, A. and Fossati, L. and Fridlund, M. and Gandolfi, D. and Gazeas, K. and Gillon, M. and Güdel, M. and Gutermann, P. and Hasiba, J. 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 Leleu, A. and Lendl, M. and Magrin, D. and Maxted, P. F. L. and Merin, B. and Mordasini, C. and Munari, M. and Nascimbeni, V. and Olofsson, G. and Ottensamer, R. and Pagano, I. and Palle, E. and Peter, G. and Piazza, D. and Piotto, G. and Pollacco, D. and Queloz, D. and Ragazzoni, R. and Rando, N. and Rauer, H. and Ribas, I. and Santos, N. C. and Ségransan, D. and Stalport, M. and Sulis, S. 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. and Zingales, T. (2025) The CHEOPS view of HD 95338b: Refined transit parameters, and a search for exomoons. Astronomy and Astrophysics, 701, A240. EDP Sciences. doi: 10.1051/0004-6361/202554040. ISSN 0004-6361.

PDF - Published version
16MB

Official URL: https://www.aanda.org/articles/aa/full_html/2025/09/aa54040-25/aa54040-25.html

Abstract

Context. Despite the ever-increasing number of known exoplanets, no uncontested detections have been made of their satellites, known as exomoons. Aims. The quest to find exomoons is at the forefront of exoplanetary sciences. Certain space-born instruments are thought to be suitable for this purpose. We show the progress made with the CHaracterising ExOPlanets Satellite (CHEOPS) in this field using the HD 95338 planetary system. We present a novel methodology as an important step in the quest to find exomoons. Methods. We utilised ground-based spectroscopic data in combination with Gaia observations to obtain precise stellar parameters. These were then used as input in the analysis of the planetary transits observed by CHEOPS and the Transiting Exoplanet Survey Satellite (TESS). In addition, we searched for the signs of satellites primarily in the form of additional transits in the Hill sphere of the eccentric Neptune-sized planet HD 95338b in a sequential approach based on four CHEOPS visits. We also briefly explored the transit timing variations of the planet. Results. We present refined stellar and planetary parameters, narrowing down the uncertainty on the planet-to-star radius ratio by a factor of ten. We also pin down the ephemeris of HD 95338b. Using injection-and-retrieval tests, we show that a 5σ detection of an exomoon would be possible at RMoon = 0.8 R⊕ with the methodology presented here. Conclusions. We exclude the transit of an exomoon in the HD 95338 system with RMoon ≈0.6 R⊕ at the 1σ level. The algorithm used for finding the transit-like event can be used as a baseline for other similar targets, observed by CHEOPS or other missions.

Item URL in elib:

https://elib.dlr.de/217982/

Document Type:

Article

Title:

The CHEOPS view of HD 95338b: Refined transit parameters, and a search for exomoons

Authors:

Authors	Institution or Email of Authors	Author's ORCID iD	ORCID Put Code
Kálmán, Sz.	HUN-REN, Research Centre for Astronomy and Earth Sciences, Konkoly Observatory, MTA Centre of Excellence, H-1121 Budapest, Konkoly Thege Mikl ´os ´ut 15-17, Hungary	UNSPECIFIED	UNSPECIFIED
Simon, A. E.	Center for Space and Habitability, University of Bern, Switzerland	UNSPECIFIED	UNSPECIFIED
Deline, A.	Observatoire de Genève, University of Geneva, Switzerland	UNSPECIFIED	UNSPECIFIED
Csizmadia, Sz.	UNSPECIFIED	https://orcid.org/0000-0001-6803-9698	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
Ehrenreich, D.	Observatoire de Genève, University of Geneva, Switzerland	UNSPECIFIED	UNSPECIFIED
Wilson, T. G.	Department of Physics, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL, UK	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
Heitzmann, A.	Observatoire Astronomique de l'Université de Genève, Chemin Pegasi 51, 1290, Versoix, Switzerland	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
Farnir, M.	Space sciences, Technologies and Astrophysics Research (STAR) Institute, Université de Liège, Allée du 6 Août 19C, 4000 Liège, Belgium	UNSPECIFIED	UNSPECIFIED
Bonfanti, A.	Space Research Institute, Austrian Academy of Sciences, Austria	UNSPECIFIED	UNSPECIFIED
Smith, A. M. S.	UNSPECIFIED	https://orcid.org/0000-0002-2386-4341	UNSPECIFIED
Pal, A.	Konkoly Observatory, Hungary	UNSPECIFIED	UNSPECIFIED
Scandariato, G.	INAF, Osservatorio Astrofisico di Catania, Via S. Sofia 78, I-95123 Catania, 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
Brandeker, A.	Department of Astronomy , Stockholm University, SE-106 91 Stockholm, Sweden	UNSPECIFIED	UNSPECIFIED
Charnoz, S.	Université de Paris, Institut de physique du globe de Paris, CNRS, F-75005 Paris, France	UNSPECIFIED	UNSPECIFIED
Akinsanmi, B.	Observatoire astronomique de l'Université de Genève, chemin Pegasi 51, 1290, Versoix, Switzerland	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
Song, X.	Observatoire astronomique de l'Université de Genève, Chemin Pegasi 51, 1290, Versoix, Switzerland; Laboratory for Climate and Ocean-Atmosphere Studies, Department of Atmospheric and Oceanic Sciences, School of Physics, Peking University, Beijing, 100871,	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
Navascues, D. Barrado	Depto. de Astrofisica, Centro de Astrobiologia (CSIC-INTA), ESAC campus, 28692, Villanueva de la Cañada (Madrid), Spain	UNSPECIFIED	UNSPECIFIED
Baumjohann, W.	Space Research Institute, Austrian Academy of Sciences, Austria	UNSPECIFIED	UNSPECIFIED
Benz, W.	Physikalisches Institut, University of Bern, Schweiz	UNSPECIFIED	UNSPECIFIED
Billot, N.	Observatoire de Genève, University of Geneva, Switzerland	UNSPECIFIED	UNSPECIFIED
Biondi, F.	INAF - Osservatorio Astronomico di Padova, Vicolo dell'Osservatorio 5, 35122 Padova, Italy	UNSPECIFIED	UNSPECIFIED
Borsato, L.	INAF Astronomical Observatory of Padova, Padova, Italy	UNSPECIFIED	UNSPECIFIED
Broeg, C.	Physikalisches Institut, University of Bern, Bern, Switzerland	UNSPECIFIED	UNSPECIFIED
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
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, CNES, LAM, Marseille, France	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
Egger, J. A.	Physikalisches Institut, University of Bern, Gesellschaftsstrasse 6, 3012, Bern, Switzerland	UNSPECIFIED	UNSPECIFIED
Erikson, A.	UNSPECIFIED	UNSPECIFIED	UNSPECIFIED
Fortier, A.	Physikalisches Institut, University of Bern, Bern, Switzerland	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
Fridlund, M.	Department of Space, Earth and Environment, Chalmers University of Technology, Onsala Space Observatory, 439 92 Onsala, Sweden; Leiden Observatory, University of Leiden, PO Box 9513, 2300 RA Leiden, The Netherlands	UNSPECIFIED	UNSPECIFIED
Gandolfi, D.	Dipartimento di Fisica, Universita degli Studi di Torino, via Pietro Giuria 1, 10125, Torino, Italy	https://orcid.org/0000-0001-8627-9628	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'Astrophsique et de Geophysique, Liege, BE	UNSPECIFIED	UNSPECIFIED
Güdel, M.	University of Vienna, Department of Astrophysics, Türkenschanzstrasse 17, 1180, Vienna, Austria	UNSPECIFIED	UNSPECIFIED
Gutermann, P.	Aix-Marseille Université, CNRS, CNES, Laboratoire d'Astrophysique de Marseille, 38 rue Frédéric Joliot-Curie, 13388, Marseille, France; Division Technique, Institut National des Sciences de l'Univers (INSU), CS 20330, 83507, La Seyne-sur-Mer, France	UNSPECIFIED	UNSPECIFIED
Hasiba, J.	Space Research Institute, Austrian Academy of Sciences, Schmiedlstraße 6, 8042, Graz, 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.	UNSPECIFIED	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
Leleu, A.	Observatoire Astronomique de l’Université de Genève, CheminPegasi 51, Versoix, Switzerland	UNSPECIFIED	UNSPECIFIED
Lendl, M.	Observatoire de Genève, Université de Genève, Chemin Pegasi, 51, 1290, Versoix, Switzerland	UNSPECIFIED	UNSPECIFIED
Magrin, D.	INAF,OsservatorioAstronomicodiPadova,Vicolodell’Osservatorio 5, 35122 Padova, Italy	UNSPECIFIED	UNSPECIFIED
Maxted, P. F. L.	Astrophysics Group, Keele University, UK	UNSPECIFIED	UNSPECIFIED
Merin, B.	ESA/ESTEC, Niederlande	UNSPECIFIED	UNSPECIFIED
Mordasini, C.	Physikalisches Institut, University of Bern, Gesellschaftsstrasse 6, 3012, Bern, Switzerland	UNSPECIFIED	UNSPECIFIED
Munari, M.	INAF - Osservatorio Astrofisico di Catania, Via S. Sofia 78, 95123 Catania, Italy	UNSPECIFIED	UNSPECIFIED
Nascimbeni, V.	INAF, Osservatorio Astrofisico di Catania, Via S. Sofia 78, I-95123 Catania, Italy	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 Astrofisica de Canarias (IAC), 38205, La Laguna, Tenerife, Spain; Departamento de Astrofisica, Universidad de La Laguna (ULL), 38206, La Laguna, Tenerife, Spain	UNSPECIFIED	UNSPECIFIED
Peter, G.	UNSPECIFIED	https://orcid.org/0000-0001-6101-2513	UNSPECIFIED
Piazza, D.	Physikalisches Institut,University of Bern, Sidlerstraße 5, CH-3012 Bern, Switzerland	UNSPECIFIED	UNSPECIFIED
Piotto, G.	INAF – Osservatorio Astronomico di Padova, vicolo dell Osservatorio 5, 35122 Padova, Italy	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.	UNSPECIFIED	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
Ségransan, D.	Geneva Observatory, University of Geneva, Chemin Pegasi 51, CH-1290 Versoix, Switzerland	UNSPECIFIED	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
Udry, S.	Geneva Observatory, University of Geneva, Chemin Pegasi 51, CH-1290 Versoix, Switzerland	UNSPECIFIED	UNSPECIFIED
Ulmer, B.	Institute of Optical Sensor Systems, German Aerospace Center (DLR), Rutherfordstrasse 2, 12489, Berlin, Germany	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
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

Date:

2025

Journal or Publication Title:

Astronomy and Astrophysics

Refereed publication:

Yes

Open Access:

Yes

Gold Open Access:

In SCOPUS:

Yes

In ISI Web of Science:

Yes

Volume:

701

DOI:

10.1051/0004-6361/202554040

Page Range:

A240

Publisher:

EDP Sciences

ISSN:

0004-6361

Status:

Published

Keywords:

methods: data analysis, techniques: photometric, planets and satellites: individual: HD 95338b, 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

Institutes and Institutions:

Institute of Planetary Research > Extrasolar Planets and Atmospheres
Institute of Planetary Research > Leitungsbereich PF
Institute of Optical Sensor Systems > Space Instruments

Deposited By:

Smith, Dr Alexis M S

Deposited On:

24 Oct 2025 08:05

Last Modified:

24 Oct 2025 08:05

Repository Staff Only: item control page