TOI-1743 b, TOI-5799 b, TOI-5799 c, and TOI-6223 b: TESS discovery and validation of four super-Earth to Neptune-sized planets around M dwarfs

¹ Astrobiology Research Unit, Université de Liège, Allée du 6 Août 19C, 4000 Liège, Belgium
² Department of Astronomy & Space Sciences, Faculty of Science, Ankara University, 06100 Ankara, Türkiye
³ Ankara University, Astronomy and Space Sciences Research and Application Center (Kreiken Observatory), Incek Blvd., 06837 Ahlatlibel, Ankara, Türkiye
⁴ Ankara University, Graduate School of Natural and Applied Sciences, Department of Astronomy and Space Sciences, Ankara, Türkiye
⁵ Instituto de Astrofísica de Canarias (IAC), Calle Vía Láctea s/n, 38200 La Laguna, Tenerife, Spain
⁶ Department of Earth, Atmospheric and Planetary Science, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
⁷ Instituto de Astrofísica de Andalucía (IAA-CSIC), Glorieta de la Astronomía s/n, 18008 Granada, Spain
⁸ School of Physics & Astronomy, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
⁹ Department of Physics and Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
¹⁰ Department of Astronomy & Astrophysics, UC San Diego, La Jolla, CA 92093, USA
¹¹ School of Physics, Faculty of Science, University of New South Wales, Kensington, Sydney, NSW 2052, Australia
¹² INAF – Palermo Astronomical Observatory, Piazza del Parlamento, 1, 90134 Palermo, Italy
¹³ Center for Astrophysics | Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USA
¹⁴ Cadi Ayyad University, Oukaimeden Observatory, High Energy Physics, Astrophysics and Geoscience Laboratory, Faculty of sciences Semlalia, Marrakech, Morocco
¹⁵ Department of Physics and Astronomy, University of Kansas, Lawrence, KS 66045, USA
¹⁶ NASA Exoplanet Science Institute-Caltech/IPAC, Pasadena, CA 91125, USA
¹⁷ Paris Region Fellow, Marie Sklodowska-Curie Action
¹⁸ AIM, CEA, CNRS, Université Paris-Saclay, Université de Paris, 91191 Gif-sur-Yvette, France
¹⁹ Center for Space and Habitability, University of Bern, Gesellschaftsstrasse 6, 3012 Bern, Switzerland
²⁰ Department of Physics and McDonnell Center for the Space Sciences, Washington University, St. Louis, MO 63130, USA
²¹ NSF NOIRLab, 950 N. Cherry Ave., Tucson, AZ 85719, USA
²² Departamento de Astrofísica, Universidad de La Laguna (ULL), 38206 La Laguna, Tenerife, Spain
²³ Komaba Institute for Science, The University of Tokyo, 3-8-1 Komaba, Meguro, Tokyo 153-8902, Japan
²⁴ Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109, USA
²⁵ Grand Pra Observatory, 1984 Les Hauderes, Switzerland
²⁶ Universidad Nacional Autónoma de México, Instituto de Astronomía, AP 70-264, CDMX 04510, Mexico
²⁷ Department of Multi-Disciplinary Sciences, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro, Tokyo 153-8902, Japan
²⁸ Okayama Observatory, Kyoto University, 3037-5 Honjo, Kamogatacho, Asakuchi, Okayama 719-0232, Japan
²⁹ Cavendish Laboratory, JJ Thomson Avenue, Cambridge CB3 0HE, UK
³⁰ NASA Ames Research Center, Moffett Field, CA 94035, USA
³¹ Space Sciences, Technologies and Astrophysics Research (STAR) Institute, Université de Liège, Allée du 6 Août 19C, 4000 Liège, Belgium
³² Department of Physical Sciences, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan
³³ Département d’Astronomie, Université de Genéve, Chemin Pegasi 51, 1290 Versoix, Switzerland
³⁴ Astrobiology Center, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan
³⁵ Institute for Particle Physics and Astrophysics, ETH Zürich, Wolfgang-Pauli-Strasse 2, 8093 Zürich, Switzerland
³⁶ Universidad Nacional Autónoma de México, Instituto de Astronomía, AP 106, Ensenada 22800, BC, Mexico
³⁷ Lowell Observatory, 1400 W Mars Hill Road, Flagstaff, AZ, 86001, USA
³⁸ Kotizarovci Observatory, Sarsoni 90, 51216 Viskovo, Croatia
³⁹ Sternberg Astronomical Institute, Lomonosov Moscow State University, 119992 Universitetskii prospekt 13, Moscow, Russia
⁴⁰ Department of Physics, Engineering and Astronomy, Stephen F. Austin State University, 1936 North St, Nacogdoches, TX 75962, USA

^★ Corresponding authors: selcuk_yalcinkaya@yahoo.com; khalid.barkaoui@uliege.be

Received: 7 July 2025
Accepted: 4 September 2025

Abstract

We present the discovery by the TESS mission of one transiting Neptune-sized planet, TOI-6223 b, and two transiting super-Earths, TOI-1743 b and TOI-5799 b. We validate these planets using a statistical validation method, multi-color light curves, and other ancillary observations. We combined TESS and ground-based photometric data to constrain the physical properties of the planets. TOI-6223 b is slightly larger than Neptune R_p = 5.12_−0.25^+0.24 R_⊕) orbiting an early M dwarf in 3.86 days, and it has an equilibrium temperature of T_eq = 714 ± 14 K. TOI-1743 b orbits its mid-dwarf star every 4.27 days. It has a radius of R_p = 1.83_−0.10^+0.11 R_⊕ and an equilibrium temperature of T_eq = 485₋₁₃⁺¹⁴. TOI-5799 b has a radius of R_p = 1.733_−0.090^+0.096 R_⊕ and an equilibrium temperature of T_eq = 505 ± 16 K. It orbit around an M2 dwarf in 4.17 days. We also present the discovery of an additional transiting planet, TOI-5799 c, which we identified in the TESS data and validated using the SHERLOCK pipeline. TOI-5799 c is a super-Earth with a radius of R_p = 1.76_−0.10^+0.11 R_⊕. Its orbital period and its equilibrium temperature are 14.01 days and T_eq = 337 ± 11 K, respectively, which place it near the inner edge of the habitable zone of its star. We show that these planets are suitable for both radial velocity follow-up and atmospheric characterization. They orbit bright (<11 K_mag) early M dwarfs, making them accessible for precise mass measurements. The combination of the planet sizes and stellar brightness of their host stars also make them suitable targets for atmospheric exploration with the JWST. Such studies may provide insights into planet formation and evolution, as TOI-1743 b, TOI-5799 b, and TOI-5799 c lie within what is known as the radius valley, while TOI-6223 b is located on the Neptunian ridge in the period-radius plane.