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Updated: May 23, 2026

An Externally-Heated Diamond Anvil Cell for Synthesis and Single-Crystal Elasticity Determination of Ice-VII at High Pressure-Temperature Conditions
Published on: June 18, 2020
Probing the interiors of the ice giants: shock compression of water to 700 GPa and 3.8 g/cm³
M D Knudson1, M P Desjarlais, R W Lemke
1Sandia National Laboratories, Albuquerque, New Mexico 87185, USA.
Abstract:
Recently, there has been a tremendous increase in the number of identified extrasolar planetary systems. Our understanding of their formation is tied to exoplanet internal structure models, which rely upon equations of state of light elements and compounds such as water. Here, we present shock compression data for water with unprecedented accuracy that show that water equations of state commonly used in planetary modeling significantly overestimate the compressibility at conditions relevant to planetary interiors. Furthermore, we show that its behavior at these conditions, including reflectivity and isentropic response, is well-described by a recent first-principles based equation of state. These findings advocate that this water model be used as the standard for modeling Neptune, Uranus, and "hot Neptune" exoplanets and should improve our understanding of these types of planets.
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