TOI-4616 b: a benchmark Earth-sized planet transiting a nearby M4 dwarf
Abstract
Rocky exoplanets are particularly abundant around M-type stars. Their small radii and low luminosities provide favourable conditions for detecting transiting terrestrial planets and probing their atmospheric properties. We report the discovery and statistical validation of TOI-4616 b, an Earth-sized planet transiting a nearby mid-M dwarf observed by the Transiting Exoplanet Survey Satellite (TESS). We confirm the planetary nature of the signal and determine the system parameters by combining TESS photometry with ground-based multi-band transit observations, high-resolution imaging, and optical and near-infrared spectroscopy. The host star lies at a distance of 28.10 +(-) 0.07 pc and has a radius of 0.1889 +(-)0.0096 solar radii, a mass of 0.1881 +(-) 0.0094 solar masses, and an effective temperature of 3150 +(-) 75 K. TOI-4616 b has a radius of 1.22 Earth radii and an orbital period of 1.55 days. The planet receives an incident flux of approximately 40 times that of Earth, corresponding to an equilibrium temperature of about 525 K. This places TOI-4616 b in a regime intermediate between Earth-sized planets orbiting early M dwarfs and those around ultra-cool hosts. Statistical validation with the TRICERATOPS framework, supported by high-resolution imaging and chromatic transit constraints, yields a false-positive probability of 0.0135, below the recommended validation threshold of 0.015, confirming TOI-4616 b as a validated planet. Owing to its proximity to Earth, well-constrained stellar properties, and extensive multi-band follow-up, TOI-4616 b constitutes a valuable benchmark system for comparative studies of terrestrial planets around mid-M dwarfs and for future atmospheric investigations.
Keywords
Cite
@article{arxiv.2603.10905,
title = {TOI-4616 b: a benchmark Earth-sized planet transiting a nearby M4 dwarf},
author = {F. Zong Lang and B. O. Demory and Y. Gomez Maqueo Chew and Y. Schmid and M. Timmermans and F. J. Pozuelos and M. Gillon and Artem Y. Burdanov and Benjamin V. Rackham and Didier Queloz and Keivan G. Stassun and Khalid Barkaoui and Amaury Triaud and Julien de Wit and S. Zuniga-Fernandez and A. J. Burgasser and Elsa Ducrot and Madison G. Scott and D. Sebastian and A. Soubkiou and M. Lendl and I. Plauchu-Frayn and U. Schroffenegger and Erik Meier V. and P. Pedersen and A. Khandelwal and Roman Gerasimov and C. Aganze and Chih-Chun Hsu and J. M. Jenkins and Aishwarya R. Iyer and C. Watkins and C. A. Theissen and K. A. Collins and H. P. Osborn and A. Shporer and Claudia Jano Munoz and Toshi Suganuma and Norio Narita and Akihiko Fukui and F. Murgas and J. de Leon and Enric Palle and Yasmin Davis and D. Kitzmann and M. Pichardo Marcano and M. J. Hooton},
journal= {arXiv preprint arXiv:2603.10905},
year = {2026}
}
Comments
Submitted to MNRAS, 22 pages, 24 figures, 3 tables