Mass-radius diagram of exoplanets with accurate mass and radius determination (Otegi et al. 2020a). Also shown are the composition lines of iron, an Earth-like planet, pure water, and 95% water + 5% H–He subjected to an insolation flux of 20S_⊕ (similar to that of TOI-269b). The EOSs used for the iron core are taken from Hakim et al. (2018), the EOS of the silicate-mantle is calculated with PERPLE_X from Connolly (2009), and for pure-water the AQUA EOS from Haldemann et al. (2020) is used.