TOI-1846b: A super-Earth In The Radius Valley Orbiting A Nearby M dwarf

We present the discovery and validation of a super-Earth planet orbiting the M dwarf star TOI-1846 (TIC 198385543).

The host star (𝐾_mag = 9.6) is located 47 pc away and has a radius of 𝑅_★ = 0.41±0.01 R_⊙, a mass of 𝑀_★ = 0.40±0.02 M_⊙ and an effective temperature of 𝑇_eff = 3568 ± 44K.

Our analyses are based on joint modelling of TESS photometry and ground-based multi-color photometric data. We also use high-resolution imaging and archival images, as well as statistical validation techniques to support the planetary system nature.

We find that TOI-1846 b is a super-Earth sized planet with radius of 𝑅_𝑝 = 1.79 ± 0.07 R_⊕ and a predicted mass of 𝑀_𝑝 = 4.4 +1.6 −1.0 M_⊕ (from the Chen & Kipping relation) on a 3.9 d orbit, with an equilibrium temperature of 𝑇_eq = 589±20𝐾 (assuming a null Bond Albedo) and an incident flux of 𝑆_𝑝 = 17.6±2.0 𝑆_⊕.

Based on the two RV measurements obtained with the TRES spectrograph and high-resolution imaging, a non-planetary transiting companion is excluded. With a radius of ≈1.8R_⊕, TOI-1846 b is within the sparsely populated radius range around 2 R_⊕ known as the radius gap (or radius valley).

This discovery can contribute to refining the precise location of the radius valley for small planets orbiting bright M dwarfs, thereby enhancing our understanding of planetary formation and evolution processes.

Abderahmane Soubkiou, Khalid Barkaoui, Zouhair Benkhaldoun, Mourad Ghachoui, Jamila Chouqar, Benjamin V. Rackham, Adam Burgasser, Emma Softich, Enric Pallé, Akihiko Fukui, Norio Narita, Felipe Murgas, Steve B. Howell, Catherine A. Clark, Colin Littlefield, Allyson Bieryla, Andrew W. Boyle, David Ciardi, Karen Collins, Kevin I. Collins, Jerome de Leon, Courtney D. Dressing, Jason Eastman, Emma Esparza-Borges, Steven Giacalone, Holden Gill, Michaël Gillon, Kai Ikuta, J. M. Jenkins, Taiki Kagetani, David W. Latham, Mayuko Mori, Hannu Parviainen, Emily Pass, G. Ricker, Boris S. Safonov, Arjun B. Savel, Richard P. Schwarz, Sara Seager, Ivan A. Strakhov, Gregor Srdoc, R. Vanderspek, Noriharu Watanabe, Cristilyn N. Watkins, J. Winn

Comments: 21 pages, 20 figures, accepted for publication in MNRAS
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2506.18550 [astro-ph.EP] (or arXiv:2506.18550v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2506.18550
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Submission history
From: Abderahmane Soubkiou
[v1] Mon, 23 Jun 2025 11:58:37 UTC (5,887 KB)
https://arxiv.org/abs/2506.18550
Astrobiology