TS23/McDonald and FIES/NOT strike again: Two new warm Jupiter systems and outer companions in a third
Journal article, 2026
Context. Gas giant planets with orbital periods of P∼8–200 d, known as warm Jupiters, are thought to be largely unaffected by the tidal interactions that can often erase valuable information on the dynamical histories of hot Jupiters. Their orbital eccentricities (e) and stellar obliquities are therefore expected to be preserved, making them valuable probes of giant-planet formation and migration. Aims. Our aim is to identify and characterise transiting warm Jupiters and expand the sample of well-characterised systems and enable further studies of giant-planet formation and migration. Methods. We analysed TESS transit photometry, together with ground-based radial velocity (RV) measurements. We performed a joint fit of the photometric and spectroscopic data from the TS23 and FIES spectrographs to determine the planetary and orbital parameters. Results. We report on the discovery and characterisation of two new, transiting warm Jupiters; TOI-5120 b (Mp = 1.23 ± 0.05 MJ , Rp = 0.969 ± 0.017 RJ , P = 24.91645 ± 0.00002 d, e = 0.10 ± 0.02) and TOI-5699 b (Mp = 0.25 ± 0.03 MJ , Rp = 0.996 ± 0.015 RJ , P = 22.01850 ± 0.00004 d, e = 0.30−0.08 +0.09). We also refined the parameters of the known warm Jupiter TOI-2158 b (Mp = 0.87 ± 0.04 MJ , R = 0.899 ± 0.015 RJ , P = 8.60079−0.00001 +0.00002 d, e = 0.028−0.014 +0.013). In addition, we detected an outer planetary companion, TOI-2158 c (Mp sin i = 1.62 ± 0.13 MJ , P = 414.5−1.6 +1.5 d, e = 0.54 ± 0.04), and identified a long-term RV trend that could indicate another planetary companion on a wide orbit. Conclusions. The diverse architectures of these systems, particularly the presence and absence of outer companions, highlight the range of dynamical pathways leading to warm Jupiters.
planets and satellites: formation
planets and satellites: dynamical evolution and stability
planets and satellites: detection
planets and satellites: gaseous planets
Author
E. Knudstrup
Aarhus University
D. Gandolfi
University of Turin
William D. Cochran
University of Texas
M. Endl
University of Texas
P. MacQueen
University of Texas
Teznie Pugh
University of Texas
Mia Sloth Lundkvist
Aarhus University
Carina Persson
Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics
Amalie Stokholm
University of Birmingham
Mark L. Winther
Aarhus University
J. R. Larsen
Aarhus University
Jakob L. Rørsted
Aarhus University
Simon Albrecht
Aarhus University
Karen A. Collins
Harvard-Smithsonian Center for Astrophysics
Cristilyn N. Watkins
Montana State University
Billy Edwards
University College London (UCL)
Netherlands Institute for Space Research (SRON)
D. R. Ciardi
National Aeronautics and Space Administration (NASA)
Catherine A. Clark
National Aeronautics and Space Administration (NASA)
A. S. Polanski
Lowell Observatory
C. Ziegler
Stephen F. Austin State University
C. Briceño
Cerro Tololo Inter American Observatory
A. Mann
The University of North Carolina System
M.E. Everett
NSF's National Optical-Infrared Astronomy Research Laboratory (NOIRLab)
S.B. Howell
National Aeronautics and Space Administration (NASA)
B. S. Safonov
Moscow State University
Tianjun Gan
University of La Laguna
Instituto de Astrofísica de Canarias
Khalid Barkaoui
Massachusetts Institute of Technology (MIT)
University of Liège
Instituto de Astrofísica de Canarias
P. Benni
Acton Sky Portal (Private Observatory)
R. Schwarz
Harvard-Smithsonian Center for Astrophysics
Keith Horne
University of St Andrews
Ramotholo Sefako
South African Astronomical Observatory
D. Muthukrishna
Massachusetts Institute of Technology (MIT)
AstroAI
Astronomy and Astrophysics
0004-6361 (ISSN) 1432-0746 (eISSN)
Vol. 714 A496Subject Categories (SSIF 2025)
Astronomy, Astrophysics, and Cosmology
DOI
10.1051/0004-6361/202661610