TOI-1736 and TOI-2141: Two systems including sub-Neptunes around solar analogs revealed by TESS and SOPHIE^★,★★

¹ Laboratório Nacional de Astrofísica, Rua Estados Unidos 154, 37504-364 Itajubá, MG, Brazil
e-mail: emartioli@lna.br
² Institut d’Astrophysique de Paris, CNRS, UMR 7095, Sorbonne Université, 98 bis bd Arago, 75014 Paris, France
³ Observatoire de Haute-Provence, St Michel l’Observatoire, France
⁴ Université Grenoble Alpes, CNRS, IPAG, 414 rue de la Piscine, 38400 St-Martin-d’Hères, France
⁵ Aix-Marseille Univ., CNRS, CNES, LAM, 38 rue Frédéric Joliot-Curie, 13388 Marseille, France
⁶ Instituto de Astrofísica e Ciências do Espaço, Universidade do Porto, CAUP, Rua das Estrelas, 4150-762 Porto, Portugal
⁷ Departamento de Física e Astronomia, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre, 4169-007 Porto, Portugal
⁸ LESIA, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Université Paris-Cité, 5 place Jules Janssen, 92195 Meudon, France
⁹ Université de Toulouse, CNRS, IRAP, 14 avenue Belin, 31400 Toulouse, France
¹⁰ Center for Astrophysics – Harvard & Smithsonian, 60 Garden Street, Cambridge, Massachusetts, MA 02138, USA
¹¹ Hazelwood Observatory, Victoria, Australia
¹² Department of Physics and Astronomy, Vanderbilt University, Nashville, TN 37235, USA
¹³ Department of Physics, Engineering and Astronomy, Stephen F. Austin State University, 1936 North St, Nacogdoches, TX 75962, USA
¹⁴ Cerro Tololo Inter-American Observatory, Casilla 603, La Serena, Chile
¹⁵ Department of Physics and Astronomy, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3255, USA
¹⁶ Astrophysics Group, University of Exeter, Exeter EX4 2QL, UK
¹⁷ Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544, USA
¹⁸ SETI Institute, Mountain View, CA 94043 USA/NASA Ames Research Center, Moffett Field, California, CA 94035, USA
¹⁹ NASA Exoplanet Science Institute, Caltech IPAC, 1200 E. California Blvd., Pasadena, California, CA 91125, USA
²⁰ NASA Ames Research Center, Moffett Field, California, CA 94035, USA

Received: 17 August 2023
Accepted: 6 October 2023

Abstract

Planetary systems around solar analogs inform us about how planets form and evolve in Solar System-like environments. We report the detection and characterization of two planetary systems around the solar analogs TOI-1736 and TOI-2141 using TESS photometry data and spectroscopic data obtained with the SOPHIE instrument on the 1.93 m telescope at the Observatoire de Haute-Provence (OHP). We performed a detailed spectroscopic analysis of these systems to obtain the precise radial velocities (RV) and physical properties of their host stars. TOI-1736 and TOI-2141 each host a transiting sub-Neptune with radii of 2.44 ± 0.18 R_⊕ and 3.05 ± 0.23 R_⊕, orbital periods of 7.073088(7) days and 18.26157(6) days, and masses of 12.8 ± 1.8 M_⊕ and 24 ± 4 M_⊕, respectively. TOI-1736 shows long-term RV variations that are consistent with a two-planet solution plus a linear trend of −0.177 m s⁻¹ day⁻¹. We measured an RV semi-amplitude of 201.1 ± 0.7 m s⁻¹ for the outer companion, TOI-1736 c, implying aprojected mass of m_csin i = 8.09 ± 0.20 M_Jup. From the Gaia DR3 astrometric excess noise, we constrained the mass of TOI-1736 c at 8.7_−0.6^+1.5 M_Jup. This planet is in an orbit of 570.2 ± 0.6 days with an eccentricity of 0.362 ± 0.003 and a semi-major axis of 1.381 ± 0.017 au, where it receives a flux of 0.71 ± 0.08 times the bolometric flux incident on Earth, making it an interesting case of a supergiant planet that has settled into an eccentric orbit in the habitable zone of a solar analog. Our analysis of the mass-radius relation for the transiting sub-Neptunes shows that both TOI-1736 b and TOI-2141 b likely have an Earth-like dense rocky core and a water-rich envelope.