On the Structure and Long-term Evolution of Ice-rich Bodies

The interest in the structure of ice-rich planetary bodies, particular differentiation between ice and rock, has grown due to discovery Kuiper belt objects exoplanets. We thus carry out a parameter study for range masses $M$, yielding radii $50 \aplt R 3000$~km, rock/ice mass ratios 0.25 4, evolving them 4.5~Gyr cold environment, obtain present structure. use thermal evolution model that allows liquid vapor flow porous medium, solving energy conservation equations under hydrostatic equilibrium spherical body orbit around central star. includes effect pressure on porosity melting temperature, heating by long-lived radioactive isotopes, temperature-dependent serpentinization dehydration. boundary space [size, rock-content] bodies differentiate, forming rocky core, those which remain undifferentiated: small with low rock content, largest considered, develop high internal pressures barely attain temperature. final differentiated comprises an mantle, thin dense crust below surface. discuss bulk density-radius relationship. very environment is investigated we find at ambient temperature $\sim$20~K, preserve amorphous form present.