TOI-238 and TOI-1685 light curves

Combined with TESS photometry and published RVs, we use the precise radii and masses of both planets to study their location relative to the corresponding Hot Water World triangles, perform an interior structure analysis and study the possible lifetimes of H/He and water-dominated atmospheres under these conditions. We find that TOI-238 b lies, at the 1sigma level, inside the corresponding triangle. While a pure H/He atmosphere would have evaporated after 0.4-1.3Myr, it is likely that a water-dominated atmosphere would have survived until the current age of the system, which makes TOI-238 b a promising candidate for a hot water world.

Conversely, TOI-1685 b lies below the mass-radius model for a pure silicate planet, meaning that even though a water-dominated atmosphere would be compatible both with our internal structure and evaporation analysis, we cannot rule out the planet to be a bare core.