Can Moons Exist Around The Habitable-zone Planet K2-18 b?
K2-18 b closely orbits a nearby M3 dwarf within its habitable zone, where this planet could be either a super-Earth or a mini-Neptune.
Recent studies using transit spectroscopy suggest that it is Hycean in nature, but this classification is currently controversial. We use the N-body integrator rebound and its extension library reboundx to investigate the possibility of exomoons around K2-18b.
Due to tidal interactions that induce outward migration, we find that any moons would be extremely unlikely. If formed, their lifetimes would be relatively short, not exceeding 10 Myr assuming Earth-like or Neptune-like tidal parameters for K2-18b. Recent studies estimate the stellar (and system) lifetime as 3 Gyr, which is significantly longer than the tidal migration timescale.
We show that exomoons are unlikely to survive around K2-18b due to rapid tidal-driven migration, casting doubt on moon-based habitability scenarios for short-period M-dwarf planets in general.
Shaan D. Patel, Billy Quarles, Manfred Cuntz, Nevin N. Weinberg
Comments: Accepted by Monthly Notices of the Royal Astronomical Society (MNRAS) Letters; 5 pages, including 3 figures and 2 tables
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2507.11594 [astro-ph.EP] (or arXiv:2507.11594v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2507.11594
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Submission history
From: Shaan Patel
[v1] Tue, 15 Jul 2025 16:54:53 UTC (209 KB)
https://arxiv.org/abs/2507.11594
Astrobiology, Astronomy, Exoplanet,
