Low-gravity waterworlds

Arnscheidt et al. "Atmospheric Evolution on Low-Gravity Waterworlds"
https://arxiv.org/abs/1906.10561

On sufficiently low-gravity worlds, the runaway greenhouse effect is suppressed by atmospheric expansion leading to a greater radiative area. Long-lived habitable states appear possible, though there are questions about whether a planet could actually evolve into these states. Predicted lower boundary below which the world becomes "comet-like" and cannot maintain habitability is around 0.0268 Earth masses, slightly larger than Ganymede.