"The possibility of hycean worlds, with planet-wide oceans and H2-rich atmospheres, significantly expands and accelerates the search for habitable environments elsewhere," they wrote. The researchers say that current models of hycean worlds neglect "chemical equilibration between primordial atmospheres and molten interiors." So to understand hycean worlds, it's necessary to understand how the magma ocean and hydrogen atmosphere interacted. The study included 248 model hycean planets, and calculated the energy equilibrium states for 26 separate components. The gray shaded region denotes the 10–90 wt% water mass fraction range proposed for Hycean planets by N. Madhusudhan et al.