From Earths To Super-Earths: Five New Small Planets Transiting M Dwarf Stars

Earth-sized planets transiting M dwarf stars present one of the best opportunities with current facilities for studying the atmospheric and bulk compositions of terrestrial worlds.

Here, we statistically validate five new transiting Earth and super-Earth sized planets orbiting M dwarf stars using a combination of light curves from the Transiting Exoplanet Survey Satellite, multi-color observations from Palomar and Las Cumbres Observatory, high-resolution imaging, and stellar spectroscopy.

The sample includes: TOI-5716 b, an Earth-sized planet (R_p = 0.96 ± 0.05 R_earth) with a 6.766-day orbit around a metal-poor thin-disk star ([Fe/H] = -0.54 ± 0.10); TOI-5728 b, a super-Earth (R_p = 1.31 ± 0.05 R_earth) on an 11.497-day orbit; and TOI-5736 b, a larger planet (R_p = 1.56 ± 0.07 R_earth) with an ultra-short period of just 0.649 days.

We also statistically validate a multi-planet system, TOI-5489, hosting two similarly-sized super-Earths: TOI-5489 b (R_p = 1.40 ± 0.05 R_earth) and TOI-5489 c (R_p = 1.28 ± 0.07 R_earth) with orbital periods of 3.152 and 4.921 days, respectively. Due to their longer orbital periods, TOI-5716 b and TOI-5728 b both have equilibrium temperatures ≤ 400 K, making them useful test cases for studies of atmospheric mass loss.

If TOI-5728 b is confirmed to have an Earth-like bulk composition, it would join the very small sample of rocky planets orbiting mid- to late-M dwarfs that lie below the cosmic shoreline and therefore may have retained high mean molecular weight atmospheres.

Jonathan Gomez Barrientos, Heather A. Knutson, Morgan Saidel, Michael Greklek-McKeon, W. Garrett Levine, Nicholas Saunders, Howard Isaacson, Renyu Hu, Karen A. Collins, David R. Ciardi, Polina A. Budnikova, Dmitry V. Cheryasov, Samuel W. Yee, Diogo Souto, Aida Behmard, Akihiko Fukui, Avi Shporer, Akanksha Khandelwal, Bob Massey, Brice-Oliver Demory, Catherine A. Clark, Chris Stockdale, Emily A. Gilbert, Enric Palle, Francis P. Wilkin, Felipe Murgas, Francis Zong Lang, Ilse Plauchu-Frayn, Jessie L. Christiansen, Jon M. Jenkins, Joseph D. Twicken, Keith Horne, Michaël Gillon, Monika Lendl, Michael B. Lund, Norio Narita, Pam Rowden, Ramotholo Sefako, Richard P. Schwarz, Steven Giacalone, Urs Schroffenegger, Yilen Gómez Maqueo Chew

Comments: 18 pages and 7 figures. Accepted for publication in AJ
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2512.11971 [astro-ph.EP] (or arXiv:2512.11971v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2512.11971
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Submission history
From: Jonathan Gomez Barrientos
[v1] Fri, 12 Dec 2025 19:00:07 UTC (2,147 KB)
https://arxiv.org/abs/2512.11971

Astrobiology, exoplanet,