The inflated, eccentric warm Jupiter TOI-4914 b orbiting a metal-poor star, and the hot Jupiters TOI-2714 b and TOI-2981 b

¹ Dipartimento di Fisica e Astronomia “Galileo Galilei”, Università di Padova, Vicolo dell’Osservatorio 3, 35122 Padova, Italy
² Istituto Nazionale di Astrofisica – Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, 35122 Padova, Italy
³ Department of Physics, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK
⁴ INAF – Osservatorio Astronomico di Roma, Via Frascati 33, 00078 Monte Porzio Catone (Roma), Italy
⁵ Centre for Exoplanet Science, SUPA School of Physics & Astronomy, University of St Andrews, North Haugh, St Andrews KY16 9SS, UK
⁶ Blue Skies Space SRL., Milan, Italy
⁷ INAF – Osservatorio Astrofisico di Catania, Via S. Sofia 78, 95123 Catania, Italy
⁸ Department of Physics and Astronomy, Vanderbilt University, Nashville, TN 37235, USA
⁹ Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544, USA
¹⁰ NASA Ames Research Center, Moffett Field, CA 94035, USA
¹¹ Departement d’astronomie, Université de Genève, Chemin Pegasi, 51, 1290 Versoix, Switzerland
¹² Univ. Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France
¹³ Center for Astrophysics |Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USA
¹⁴ Astrobiology Research Unit, Université de Liège, 19C Allée du 6 Août, 4000 Liège, Belgium
¹⁵ Department of Earth, Atmospheric and Planetary Science, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
¹⁶ Instituto de Astrofísica de Canarias (IAC), 38205 La Laguna, Tenerife, Spain
¹⁷ Phil Evans, El Sauce Observatory, Coquimbo Province, Chile
¹⁸ Department of Physics & Astronomy, Texas Tech University, Lubbock, TX 79409-1051, USA
¹⁹ Centro di Ateneo di Studi e Attività Spaziali “Giuseppe Colombo” (CISAS), Università degli Studi di Padova, Via Venezia 15, 35131 Padova, Italy
²⁰ Università degli Studi di Padova, Via Venezia 15, 35131 Padova, Italy
²¹ NASA Goddard Space Flight Center, 8800 Greenbelt Road, Greenbelt, MD 20771, USA
²² SETI Institute, 189 Bernardo Ave, Suite 200, Mountain View, CA 94043, USA
²³ Department of Physics and Astronomy, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
²⁴ Instituto de Astrofísica de Andalucía (IAA-CSIC), Glorieta de la Astronomía s/n, 18008 Granada, Spain
²⁵ American Association of Variable Star Observers, 49 Bay State Road, Cambridge, MA 02138, USA
²⁶ Royal Astronomical Society, Burlington House, Piccadilly, London W1J 0BQ, UK
²⁷ Department of Physics and Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
²⁸ Department of Aeronautics and Astronautics, MIT, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
²⁹ Perth Exoplanet Survey Telescope, Perth, Western Australia, Australia

^★ Corresponding author; giacomo.mantovan@unipd.it

Received: 9 August 2024
Accepted: 11 September 2024

Abstract

Recent observations of giant planets have revealed unexpected bulk densities. Hot Jupiters, in particular, appear larger than expected for their masses compared to planetary evolution models, while warm Jupiters seem denser than expected. These differences are often attributed to the influence of the stellar incident flux, but it has been unclear if they also result from different planet formation processes, and if there is a trend linking the planetary density to the chemical composition of the host star. In this work, we present the confirmation of three giant planets in orbit around solar analogue stars. TOI-2714 b (P ≃ 2.5 d, R_p ≃ 1.22 R_J, M_p = 0.72 M_J) and TOI-2981 b (P ≃ 3.6 d, R_P ≃ 1.2 R_J, M_P = 2 M_J) are hot Jupiters on nearly circular orbits, while TOI-4914 b (P ≃ 10.6 d, R_P ≃ 1.15 R_J, M_p = 0.72 M_J) is a warm Jupiter with a significant eccentricity (e = 0.41 ± 0.02) that orbits a star more metal-poor ([Fe/H] = −0.13) than most of the stars known to host giant planets. Similarly, TOI-2981 b orbits a metal-poor star ([Fe/H] = −0.11), while TOI-2714 b orbits a metal-rich star ([Fe/H] = 0.30). Our radial velocity follow-up with the HARPS spectrograph allows us to detect their Keplerian signals at high significance (7, 30, and 23σ, respectively) and to place a strong constraint on the eccentricity of TOI-4914 b (18σ). TOI-4914 b, with its large radius (R_p ≃ 1.15 R_J) and low insolation flux (F_⋆ < 2 × 108 erg s⁻¹ cm⁻²), appears to be more inflated than what is supported by current theoretical models for giant planets. Moreover, it does not conform to the previously noted trend that warm giant planets orbiting metal-poor stars have low eccentricities. This study thus provides insights into the diverse orbital characteristics and formation processes of giant exoplanets, in particular the role of stellar metallicity in the evolution of planetary systems.