PALEOS toolkit models exoplanet interiors with phase-aware equations of state

Star system: WASP-47 | Distance from the Sun: 881 light years

Understanding the interior structure of rocky and water-rich exoplanets requires accurate equations of state (EoS) that describe how materials behave under different pressures and temperatures. The new PALEOS toolkit brings together EoS for iron, magnesium silicate, and water into a unified, phase-aware framework that covers 17 different material phases. This allows scientists to model density, energy, entropy, heat capacity, and other properties across a planet's interior, from surface to core.

PALEOS is validated against Earth's structure, matching its radius and lower-mantle densities closely. The toolkit provides lookup tables for a wide range of pressures and temperatures, enabling the calculation of mass-radius relations for thousands of planet types. It can model planets from fully solid to those with deep magma oceans, showing that thermal expansion can significantly affect a planet's radius, especially at high temperatures. For example, two planets with the same mass and radius could have very different interiors—one solid and one with a magma ocean and a liquid core capable of generating a magnetic field.

These advances make it possible to translate astronomical observations into detailed models of exoplanet geophysics, improving our understanding of their composition, structure, and potential for magnetic fields.

Key findings
- PALEOS unifies equations of state for iron, silicates, and water across 17 phases
- Toolkit matches Earth's radius and mantle densities to high accuracy
- Models mass-radius relations for rocky and water-rich planets at various temperatures
- Thermal expansion can change a planet's radius by over 15% at high temperatures
- Planets with the same mass and radius can have very different interior states

Scientific study

PALEOS: Multiphase Equations of State and Mass-Radius Relations for Exoplanet Interiors (external link)