Detection and characterisation of a 106-day transiting Jupiter: TOI-2449 b/NGTS-36 b
Journal article, 2025
Context. Only a handful of transiting giant exoplanets with orbital periods longer than 100 days are known. These warm exoplanets are valuable objects, as their radius and mass can be measured and lead to an in-depth characterisation of the planet’s properties. Thanks to low levels of stellar irradiation and large orbital distances, the atmospheric properties and orbital parameters of warm exoplanets remain relatively unaltered by their host star, giving new insights into planetary formation and evolution. Aims. Our aim is to increase the sample of warm giant exoplanets with precise radii and masses. Our goal is to identify suitable candidates in the Transiting Exoplanet Survey Satellite data and perform follow-up observations with ground-based instruments. Methods. We used the Next Generation Transit Survey (NGTS) to detect additional transits of planetary candidates in order to pinpoint their orbital period. We also monitored the target with several high-resolution spectrographs to measure the planetary mass and eccentricity. We studied the planet’s interior composition with a planetary evolution code to determine the planet’s metallicity. Results. We report the discovery of a 106-day period Jupiter-sized planet around the G-type star TOI-2449/NGTS-36. We jointly modelled the photometric and radial velocity data and find that the planet has a mass of 0.70−0.04+0.05 MJ and a radius of 1.001 ± 0.009 RJ. The planetary orbit has a semi-major axis of 0.449 au and is slightly eccentric (e = 0.0098−0.030+0.028). We detected an additional 3-year signal in the radial velocity data that is likely due to the stellar magnetic cycle. Based on the planetary evolution models considered here, we find that TOI-2449 b/NGTS-36 b contains 11−5+6M⊕ of heavy elements and has a marginal planet-to-star metal enrichment of 3.3−1.8+2.5. Assuming a Jupiter-like bond albedo, TOI-2449 b/NGTS-36 b has an equilibrium temperature of 400 K and is a good target for understanding nitrogen chemistry in cooler atmospheres.
methods: data analysis
planets and satellites: individual: TOI-2449b
planets and satellites: detection
planets and satellites: gaseous planets
Author
S. Ulmer-Moll
Physics Institute
University of Geneva
Leiden University
S. Gill
The University of Warwick
Rafael Brahm
Adolfo Ibáñez University
Millennium Institute of Astrophysics
Data Observatory Foundation
A. Claringbold
The University of Warwick
M. Lendl
University of Geneva
K. Al Moulla
University of Geneva
University of Porto
D. Anderson
Universidad Catolica del Norte
M. P. Battley
University of Geneva
Queen Mary University of London
D. Bayliss
The University of Warwick
A. Bonfanti
Institut fur Weltraumforschung
F. Bouchy
University of Geneva
C. Briceño
Cerro Tololo Inter American Observatory
E. Bryant
University College London (UCL)
Matt Burleigh
University Of Leicester
Karen A. Collins
Harvard-Smithsonian Center for Astrophysics
A. Deline
University of Geneva
X. Dumusque
University of Geneva
Jan Eberhardt
Max Planck Society
Néstor Espinoza
Space Telescope Science Institute (STScI)
B. Falk
Space Telescope Science Institute (STScI)
João Pedro Faria
University of Geneva
J. Fernández Fernández
The University of Warwick
P. Figueira
University of Geneva
University of Porto
Malcolm Fridlund
Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics
Leiden University
Elise Furlan
National Aeronautics and Space Administration (NASA)
M.R. Goad
University Of Leicester
Robert Goeke
Massachusetts Institute of Technology (MIT)
J. Hagelberg
University of Geneva
F. Hawthorn
The University of Warwick
R. Helled
University of Zürich
T. Henning
Max Planck Society
Melissa J. Hobson
University of Geneva
Millennium Institute of Astrophysics
Max Planck Society
S.B. Howell
National Aeronautics and Space Administration (NASA)
M. Jafariyazani
SETI Institute
National Aeronautics and Space Administration (NASA)
Jon M. Jenkins
National Aeronautics and Space Administration (NASA)
James S. Jenkins
Centro de Astrofísica y Tecnologías Afines (CATA),
Diego Portales University
M. I. Jones
European Southern Observatory Santiago
Andrés Jordán
Adolfo Ibáñez University
Data Observatory Foundation
Millennium Institute of Astrophysics
Alicia Kendall
University Of Leicester
N. Law
The University of North Carolina System
C. Littlefield
Bay Area Environmental Research Institute (BAER)
National Aeronautics and Space Administration (NASA)
A. Mann
The University of North Carolina System
J. McCormac
The University of Warwick
C. Mordasini
University of Bern
Physics Institute
M. Moyano
Universidad Catolica del Norte
H. P. Osborn
Physics Institute
C. Pezzotti
University of Liège
A. Psaridi
University of Geneva
Spanish National Research Council (CSIC)
Centre Tecnològic de Telecomunicacions de Catalunya (CTTC)
Samuel N. Quinn
Harvard-Smithsonian Center for Astrophysics
T. Rodel
Queen's University Belfast
Joseph E. Rodriguez
Michigan State University
F. Rojas
Millennium Institute of Astrophysics
Pontificia Universidad Catolica de Chile
S. Saha
Diego Portales University
Centro de Astrofísica y Tecnologías Afines (CATA),
M. Schlecker
University of Arizona
S. Seager
Massachusetts Institute of Technology (MIT)
S.G. Sousa
University of Porto
M. Tala-Pinto
Ohio State University
Millennium Institute of Astrophysics
Adolfo Ibáñez University
T. Trifonov
Sofia University
Heidelberg-Königstuhl State Observatory
S. Udry
University of Geneva
José I. Vines
Universidad Catolica del Norte
G. Viviani
Swiss Federal Institute of Technology in Lausanne (EPFL)
Christopher Watson
Queen's University Belfast
P. J. Wheatley
The University of Warwick
T.G. Wilson
The University of Warwick
J. N. Winn
Princeton University
George Zhou
University of Southern Queensland
C. Ziegler
Stephen F. Austin State University
Astronomy and Astrophysics
0004-6361 (ISSN) 1432-0746 (eISSN)
Vol. 703 A258Subject Categories (SSIF 2025)
Astronomy, Astrophysics, and Cosmology
DOI
10.1051/0004-6361/202555168