A joint effort to discover and characterize two resonant mini-Neptunes around TOI-1803 with TESS, HARPS-N, and CHEOPS
Journal article, 2025
Context. The discovery and characterization of mini-Neptunes hold a potentially crucial impact on planetary formation and evolution theories. Estimating their orbital parameters and atmospheric properties would provide valuable hints to improve formation and atmospheric models. Aims. We present the discovery of two mini-Neptunes near a 2:1 orbital resonance configuration orbiting the K0 star TOI-1803. We describe in detail their orbital architecture and suggest some possible formation and evolution scenarios. Methods. Using CHEOPS, TESS, and HARPS-N datasets, we estimated the radius and the mass of both planets. We used a multidimensional Gaussian process with a quasi-periodic kernel to disentangle the planetary components from the stellar activity in the HARPS-N dataset. We performed dynamical modeling to explain the orbital configuration and performed planetary formation and evolution simulations. For the least dense planet, we assumed different atmospheric compositions and defined possible atmospheric scenarios with simulated JWST observations. Results. TOI-1803 b and TOI-1803 c have orbital periods of ∼6.3 and ∼12.9 days, respectively, residing in close proximity to a 2:1 orbital resonance. Ground-based photometric follow-up observations have revealed significant transit timing variations (TTV) with an amplitude of ∼10 min and ∼40 min, respectively, for planets b and -c. With the masses computed from the radial velocities dataset, we obtained a density of (0.39 ± 0.10) ρ⊕ and (0.076 ± 0.038) ρ⊕ for planets b and -c, respectively. TOI-1803 c is among the least dense mini-Neptunes currently known, and due to its inflated atmosphere, it is a suitable target for transmission spectroscopy with JWST. With NIRSpec observations, we could understand whether the planet has kept its primary atmosphere or not, which would constrain our formation models. Conclusions. We report the discovery of two mini-Neptunes close to a 2:1 orbital resonance. The detection of significant TTVs from ground-based photometry opens scenarios for a more precise mass determination. TOI-1803 c is one of the least dense mini-Neptunes known so far, and it is of great interest among the scientific community since it could constrain current formation scenarios. JWST observations could give us valuable insights to characterize this interesting system.
Planets and satellites: interiors
Planets and satellites: detection
Planets and satellites: fundamental parameters
Planets and satellites: formation
Planets and satellites: dynamical evolution and stability
Author
Tiziano Zingales
University of Padua
Luca Malavolta
University of Padua
Luca Borsato
Istituto nazionale di astrofisica (INAF)
Diego Turrini
Istituto nazionale di astrofisica (INAF)
Andrea Bonfanti
Institut fur Weltraumforschung
Danae Polychroni
Osservatorio Astronomico di Trieste
Giacomo Mantovan
University of Padua
Domenico Nardiello
University of Padua
Valerio Nascimbeni
Istituto nazionale di astrofisica (INAF)
Antonino Francesco Lanza
Istituto nazionale di astrofisica (INAF)
Anja Bekkelien
University of Geneva
Alessandro Sozzetti
Istituto nazionale di astrofisica (INAF)
Christopher Broeg
University of Bern
Luca Naponiello
Istituto nazionale di astrofisica (INAF)
Monika Lendl
University of Geneva
Aldo Stefano Bonomo
Istituto nazionale di astrofisica (INAF)
Attila E. Simon
University of Bern
Silvano Desidera
Istituto nazionale di astrofisica (INAF)
Giampaolo Piotto
University of Padua
Luigi Mancini
University of Rome Tor Vergata
Matthew J. Hooton
University of Cambridge
Andrea Bignamini
Osservatorio Astronomico di Trieste
Jo Ann Egger
University of Bern
Antonio Maggio
Istituto nazionale di astrofisica (INAF)
Yann Alibert
University of Bern
Daniele Locci
Istituto nazionale di astrofisica (INAF)
Laetitia Delrez
University of Liège
Federico Biassoni
University of Insubria
Luca Fossati
Institut fur Weltraumforschung
Lorenzo Cabona
Istituto nazionale di astrofisica (INAF)
Gaia Lacedelli
Instituto de Astrofísica de Canarias
Ilaria Carleo
Instituto de Astrofísica de Canarias
Pietro Leonardi
University of Padua
Gloria Andreuzzi
Osservatorio Astronomico di Roma
Alexis Brandeker
Stockholm University
Rosario Cosentino
Istituto nazionale di astrofisica (INAF)
Alexandre C. M. Correia
University of Coimbra
Riccardo Claudi
Istituto nazionale di astrofisica (INAF)
Roi Alonso
Instituto de Astrofísica de Canarias
Mario Damasso
Istituto nazionale di astrofisica (INAF)
Thomas G. Wilson
The University of Warwick
Tamás Bárczy
Admatis
Matteo Pinamonti
Istituto nazionale di astrofisica (INAF)
David Baker
Austin College
Khalid Barkaoui
University of Liège
David Barrado Navascués
European Space Agency (ESA)
Susana Barros
University of Porto
Wolfgang Baumjohann
Institut fur Weltraumforschung
Thomas Beck
University of Bern
Charles A. Beichman
National Aeronautics and Space Administration (NASA)
Willy Benz
University of Bern
Allyson Bieryla
Harvard-Smithsonian Center for Astrophysics
Nicolas Billot
University of Geneva
Pau Bosch-Cabot
Albanyà Astronomical Observatory
Luke Bouma
California Institute of Technology (Caltech)
David Ciardi
National Aeronautics and Space Administration (NASA)
Andrew Cameron
University of St Andrews
Karen Collins
Harvard-Smithsonian Center for Astrophysics
Ian J. M. Crossfield
University of Kansas
Szilard Csizmadia
German Aerospace Center (DLR)
Patricio Cubillos
Institut fur Weltraumforschung
Melvyn Davies
Lund University
Magali Deleuil
Laboratoire d'Astrophysique de Marseille
Adrien Deline
University of Geneva
Olivier Demangeon
University of Porto
Brice-Olivier Demory
University of Bern
Aliz Derekas
Eötvös Loránd University (ELTE)
Diana Dragomir
University of New Mexico
Billy Edwards
Netherlands Institute for Space Research (SRON)
David Ehrenreich
University of Geneva
Anders Erikson
German Aerospace Center (DLR)
Ben Falk
Space Telescope Science Institute (STScI)
Andrea Fortier
University of Bern
Malcolm Fridlund
Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics
Leiden University
Akihiko Fukui
Instituto de Astrofísica de Canarias
Davide Gandolfi
University of Turin
Kosmas Gazeas
University of Athens
Michaël Gillon
University of Liège
Erica J. Gonzales
University of California
Manuel Guedel
University of Vienna
Pere Guerra
Albanyà Astronomical Observatory
Maximilian N. Günther
European Space Agency (ESA)
Alexis Heitzmann
University of Geneva
Ch. Helling
Institut fur Weltraumforschung
Steve B. Howell
National Aeronautics and Space Administration (NASA)
Kate Isaak
European Space Agency (ESA)
Jon Jenkins
National Aeronautics and Space Administration (NASA)
Laszlo Kiss
Hungarian Academy of Sciences
Judith Korth
Lund University
Kristine Wai Fun Lam
German Aerospace Center (DLR)
Jacques Laskar
Paris Observatory
Alain Lecavelier des Etangs
Institut d 'Astrophysique de Paris
Demetrio Magrin
Istituto nazionale di astrofisica (INAF)
Rachel Matson
National Aeronautics and Space Administration (NASA)
Elisabeth Matthews
Max Planck Society
Pierre Maxted
Keele University
Scott McDermott
Protologic LLC
Matteo Munari
Istituto nazionale di astrofisica (INAF)
Christoph Mordasini
University of Bern
Norio Narita
Instituto de Astrofísica de Canarias
Göran Olofsson
Stockholm University
Roland Ottensamer
University of Vienna
Isabella Pagano
Istituto nazionale di astrofisica (INAF)
Enric Palle
Instituto de Astrofísica de Canarias
Gisbert Peter
German Aerospace Center (DLR)
Donald L. Pollacco
The University of Warwick
Didier Queloz
University of Cambridge
Roberto Ragazzoni
University of Padua
Nicola Rando
European Space Agency (ESA)
Francesco Ratti
European Space Agency (ESA)
Heike Rauer
German Aerospace Center (DLR)
Ignasi Ribas
Spanish National Research Council (CSIC)
Sébastien Salmon
University of Geneva
Nuno Santos
University of Porto
Gaetano Scandariato
Istituto nazionale di astrofisica (INAF)
Sara Seager
Massachusetts Institute of Technology (MIT)
Damien Ségransan
University of Geneva
Alexis M. S. Smith
German Aerospace Center (DLR)
Joshua E. Schlieder
National Aeronautics and Space Administration (NASA)
Richard Schwarz
Harvard-Smithsonian Center for Astrophysics
Avi Shporer
Massachusetts Institute of Technology (MIT)
S. G. Sousa
University of Porto
Manu Stalport
University of Liège
M. Steinberger
Institut fur Weltraumforschung
Sophia Sulis
Laboratoire d'Astrophysique de Marseille
Gyula Szabó
Eötvös Loránd University (ELTE)
Joseph Twicken
National Aeronautics and Space Administration (NASA)
Stephane Udry
University of Geneva
Valerie Van Grootel
University of Liège
Julia Venturini
University of Geneva
Eva Villaver
Instituto de Astrofísica de Canarias
Nicholas Walton
University of Cambridge
Joshua N. Winn
Princeton University
Astronomy and Astrophysics
0004-6361 (ISSN) 1432-0746 (eISSN)
Vol. 695 A273Subject Categories (SSIF 2025)
Astronomy, Astrophysics, and Cosmology
DOI
10.1051/0004-6361/202451180