Planetary Cores

Using laser-driven compression, a team of researchers have created an experiment that’s giving new insight into what it’s like in the cores of giant super-Earths and during the birth of earth-like planets. The experiment subjects synthetic stishovite, a high density form of silica, to laser-induced shock compression. It then measures the short-lived reaction using extremely fast diagnostics. What Lawrence Livermore National Laboratory (LLNL) physicist Marius Millot and colleagues from Bayreuth University (Germany), LLNL and the University of California, Berkeley found gave them a picture of the melting temperature of silica at around 500 GPa (gigapascal, a unit of pressure), roughly five million times the air pressure on Earth. This is comparable to the core-mantle boundary pressure of a planet about five times the mass of Earth or an Earth-like planet in the throes of the giant impacts involved in the final stage of its birth. “Deep inside planets, extreme density, pressure and temperature strongly modify the properties of the constituent materials,” Millot said. “How much heat solids can sustain before