Three hot Jupiters transiting K-dwarfs with significant heavy element masses

¹ Observatoire de Genève, 51 Ch. Pegasi, 1290 Versoix, Switzerland
² European Southern Observatory, Karl-Schwarzschild-Strasse 3, 85748 Garching, Germany
³ Leiden Observatory, Leiden University, Postbus 9513, 2300 RA Leiden, The Netherlands
⁴ Instituto de Astrofisica e Ciencias do Espaco, Universidade do Porto, CAUP, Rua das Estrelas, 4150-762 Porto, Portugal
⁵ Departamento de Fisica e Astronomia, Faculdade de Ciencias, Universidade do Porto, Rua do Campo Alegre, 4169-007 Porto, Portugal
⁶ Department of Physics and Astronomy, Vanderbilt University, Nashville, TN 37235, USA
⁷ Center for Astrophysics | Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USA
⁸ Astrobiology Research Unit, University of Liège, Allée du 6 août, 19, 4000 Liège (Sart-Tilman), Belgium
⁹ Department of Earth, Atmospheric and Planetary Science, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
¹⁰ Instituto de Astrofisica de Canarias (IAC), Calle Via Láctea s/n, 38200, La Laguna, Tenerife, Spain
¹¹ Astronomy Unit, Queen Mary University of London, G.O. Jones Building, Bethnal Green, London E1 4NS, UK
¹² Department of Physics and McDonnell Center for the Space Sciences, Washington University, St. Louis, MO 63130, USA
¹³ El Sauce Observatory, Coquimbo Province, Chile
¹⁴ Department of Physics and Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
¹⁵ Astrophysics Group, Keele University, Keele ST5 5BG, UK
¹⁶ STAR Institute, University of Liège, Allée du 6 août, 19, 4000 Liège (Sart-Tilman), Belgium
¹⁷ NASA Ames Research Center, Moffett Field, CA 94035, USA
¹⁸ Department of Physics and Astronomy, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3255, USA
¹⁹ Departamento de Astrofisica, Universidad de La Laguna (ULL), 38206 La Laguna, Tenerife, Spain
²⁰ Silesian University of Technology, Akademicka 16, 44-100 Gliwice, Poland
²¹ Instituto de Astrofisica de Andalucia (IAA-CSIC), Glorieta de la Astronomia s/n, 18008 Granada, Spain
²² Brierfield Observatory, Bowral, NSW Australia
²³ Department of Aeronautics and Astronautics, MIT, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
²⁴ Sternberg Astronomical Institute Lomonosov Moscow State University, Moscow, 119234 Russia
²⁵ Perth Exoplanet Survey Telescope, Perth, Western Australia, Australia
²⁶ SETI Institute, Mountain View, CA 94043 USA/NASA Ames Research Center, Moffett Field, CA 94035, USA
²⁷ Department of Astrophysical Sciences, Princeton University, 4 Ivy Lane, Princeton, NJ 08544, USA
²⁸ Department of Physics, Engineering and Astronomy, Stephen F. Austin State University, 1936 North St, Nacogdoches, TX 75962, USA

^★ Corresponding author: yolanda.frensch@unige.ch

Received: 24 January 2025
Accepted: 3 June 2025

Abstract

Context. Despite predictions from planetary population synthesis models indicating that such systems should be exceedingly rare, short-period gas giants do exist around low-mass stars (T_eff < 4965 K), albeit at lower frequency than around hotter stars.

Aims. By combining data from the Transiting Exoplanet Survey Satellite (TESS) and ground-based follow-up observations, we seek to confirm and characterize giant planets transiting K dwarfs, particularly mid- to late-K dwarfs.

Methods. Photometric data were obtained from the TESS mission, supplemented by ground-based imaging and photometric observations, as well as high-resolution spectroscopic data from the CORALIE spectrograph. Radial velocity (RV) measurements were analyzed to confirm the presence of companions.

Results. We report the confirmation and characterization of three giants transiting mid-K dwarfs. Within the TOI-2969 system, a giant planet of 1.16 ± 0.04 M_Jup with a radius of 1.10 ± 0.08 R_Jup orbits its K3V host in 1.82 days. The TOI-2989 system contains a 3.0 ± 0.2 M_Jup giant with a radius of 1.12 ± 0.05 R_Jup, which orbits its K4V host in 3.12 days. The K4V star TOI-5300 hosts a giant of 0.6 ± 0.1 M_Jup with a radius of 0.88 ± 0.08 R_Jup and an orbital period of 2.3 days. The equilibrium temperatures of the companions range from 1001 to 1186 K, which classifies them as hot Jupiters. However, they do not exhibit radius inflation. The estimated heavy element masses in their interiors, inferred from the mass, radius, and evolutionary models, are 90 ± 30M_⊕, 114 ± 30M_⊕, and 84 ± 21M_⊕, respectively. These heavy element masses are significantly higher than most reported heavy elements for K-dwarf hot Jupiters.

Conclusions. These mass characterizations contribute to the poorly explored population of massive companions around low-mass stars.