TESS Planet Occurrence Rates Reveal the Disappearance of the Radius Valley Around Mid-to-Late M Dwarfs

We present the deepest systematic search for planets around mid-to-late M dwarfs to date. We have surveyed 8134 mid-to-late M dwarfs observed by TESS with a custom built pipeline and recover 77 vetted transiting planet candidates.

We characterize the sensitivity of our survey via injection-recovery and measure the occurrence rate of planets as a function of orbital period, instellation, and planet radius. We measure a cumulative occurrence rate of 1.10±0.16 planets per star with radii >1R⊕ orbiting within 30 days.

This value is consistent with the cumulative occurrence rate around early M dwarfs, making M dwarfs collectively the most prolific hosts of small close-in planets. Unlike the bimodal Radius Valley exhibited by close-in planet population around FGK and early M dwarfs, we recover a unimodal planet radius distribution peaking at 1.25±0.05R_⊕.

We additionally find 0.954±0.147 super-Earths and 0.148±0.045 sub-Neptunes per star, with super-Earths outnumbering sub-Neptunes 5.5:1, firmly demonstrating that the Radius Valley disappears around the lowest mass stars.

The dearth of sub-Neptunes around mid-to-late M dwarfs is consistent with predictions from water-rich pebble accretion models that predict a fading Radius Valley with decreasing stellar mass.

Our results support the emerging idea that the sub-Neptune population around M dwarfs is composed of water-rich worlds. We find no hot Jupiters in our survey and set an upper limit of 0.012 hot Jupiters per mid-to-late M dwarf within 10 days.

Erik Gillis, Ryan Cloutier, Emily Pass

Comments: Submitted to AAS Journals February 26 2026, 25 pages, 17 Figures, 8 Tables
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2602.23364 [astro-ph.EP] (or arXiv:2602.23364v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2602.23364
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Submission history
From: Erik Gillis Mr
[v1] Thu, 26 Feb 2026 18:59:48 UTC (20,029 KB)
https://arxiv.org/abs/2602.23364

Astrobiology,