TOI-244 photometry and spectroscopy

These values correspond to a density of {rho}=4.2+/-1.1g/cm^3^, which is below what would be expected for an Earth-like composition. We find that atmospheric loss processes may have been efficient to remove a potential primordial hydrogen envelope, but high mean-molecular weight volatiles such as water could have been retained. Our internal structure modeling suggests that TOI-244 b has a 479^+128^_-96_km thick hydrosphere over a 1.17+/-0.09R_{sun}_ solid structure composed of a Fe-rich core and a silicate-dominated mantle compatible with that of the Earth.

On a population level, we find two tentative trends in the density-metallicity and density-insolation parameter space for the low-density super-Earths, which may hint at their composition. With a 8% precision in radius and 12% precision in mass, TOI-244 b is among the most precisely characterized super-Earths, which, together with the likely presence of an extended hydrosphere, makes it a key target for atmospheric observations.