As per study, The demographics of sub-Neptunes and super-Earths are driven by the miscibility of hydrogen, silicate, and iron at high pressures, which causes planets with hydrogen mass fractions > 1% to have "dilute" interiors rather than discrete metallic cores.

As per study, The demographics of sub-Neptunes and super-Earths are driven by the miscibility of hydrogen, silicate, and iron at high pressures, which causes planets with hydrogen mass fractions > 1% to have "dilute" interiors rather than discrete metallic cores.