ATHENAIA Mass-radius Relationships and Water-Hydrogen Demixing flags for Sub-Neptunes

Sub-Neptune mass-radius relationships and water-hydrogen demixing conditions This repository contains modeling results presented in Piaulet-Ghorayeb et al. (2026, in review at AAS journals) calculated with ATHENAIA. The models used temperature and radius profiles calculated by Daniel Thorngren for the interior (see paper). Mass-radius relationships We provide calculated radii for three values of T_eq (see Table 2 in the paper), across the full range of envelope mass fractions and metallicities. The Python script plot_MR_for_Zenodo.py provides an example of how to read in the grids and plot mass-radius relationships. Note: we provide a regular grid with one value of the radius for each parameter combination. If for any combination of (T_eq, envelope mass fraction f_env, envelope metallicity Z_env), the radius becomes constant below a certain value of the mass m_min, the values of the radius for m<m_min should be considered as placeholders for invalid models). Map of water-hydrogen demixing conditions in (f_env, Z_env) space We provide N-D arrays mapping the occurence of demixing across masses of 2.6 to 20 Earth masses and for three values of T_eq (see Table 2 in the paper) in (f_env, Z_env) space. The maps also encode the estimated extent of upper-atmosphere water depletion (i.e., the stable value for Z_atm) required to reach stability (see Appendix B and Figure B2 for more details). The Python script plot_demixing_maps_Zenodo.py shows how to read in the grid and plot either demixing contours, or estimates of atmosphere metal depletion due to water-hydrogen demixing.