![HZ and planetary orbits in the GJ 12 system. The extent of the HZ is shown in green, where light green and dark green indicate the CHZ and OHZ, respectively. The solid line shows the orbit with the nominal eccentricity of 0.24, and the dashed lines represent 1σ boundaries (Turner et al. 2026). The scale of the figure is 0.2 AU along each side with a 0.02 AU grid.-- [astro-ph.EP]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/08/The-Tidal-.png?fit=1200%2C672&ssl=1)
[astro-ph.EP] The demographics of terrestrial planets and their orbits reveal a vast diversity in overall planetary energy budgets.
Terrestrial exoplanets in short-period or eccentric orbits can experience intense tidal heating that, combined with stellar irradiation, may trigger runaway greenhouse conditions analogous to Venus.
We calculate tidal heating rates for 143 terrestrial-sized exoplanets with measured eccentricities and find that, under adopted archive default eccentricities and constant-Q assumptions, 70% exceed the extreme volcanism threshold in tidal flux and 96% exceed the runaway greenhouse limit in total zero-albedo flux.
We develop a three-category taxonomy of tidal influence on climate: flux-driven Venus analogs, tidally dominated planets, and historically compromised Habitable Zone (HZ) worlds, and apply this framework to five case studies.
TOI-6716 b and TOI-912 b may have exceptionally high tidal fluxes, potentially serving as examples where tidal dissipation alone causes them to exceed the runaway greenhouse threshold.
TOI-700 d and LHS 1140 b, though currently below the threshold, were exposed to above-threshold stellar irradiation during their host stars’ ∼0.5– 3∼Gyr pre-main-sequence phases; whether their atmospheres survived is testable with JWST. GJ 12 b, already above the threshold from stellar flux alone, experiences a tidal heat flux of ∼5∼W/m2 (comparable to Io) that drives an independent volcanic pathway to a runaway greenhouse.
Three-dimensional climate simulations show that a temperate atmosphere for GJ 12 b fails to achieve radiative balance, while a Venus-like CO2-dominated atmosphere converges to a stable state. We consider observational prospects for these systems and connections to forthcoming Venus in-situ missions.
Stephen R. Kane, Emma L. Miles
Comments: 27 pages, 4 figures, 2 tables, accepted for publication in ApJ
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2608.18290 [astro-ph.EP] (or arXiv:2608.18290v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2608.18290
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Submission history
From: Stephen Kane
[v1] Tue, 18 Aug 2026 20:15:04 UTC (1,208 KB)
https://arxiv.org/abs/2608.18290
Astrobiology, exoplanet,
