Ironing Out the Interiors of Super-Earth Exoplanets - SciTechDaily

An artist’s conception of the cross section of a super-Earth with the NIF target chamber superimposed over the mantle, looking into the core.

Lawrence Livermore National Laboratory (LLNL) scientists and collaborators have used lasers at the National Ignition Facility to experimentally determine the high-pressure melting curve and structural properties of pure iron up to 1,000 GPa (nearly 10,000,000 atmospheres), three times the pressure of Earth’s inner core and nearly four times greater pressure than any previous experiments.

The team performed a series of experiments that emulate the conditions observed by a parcel of iron descending toward the center of a super-Earth core.

“The iron melting curve is critical to understanding the internal structure, thermal evolution, as well as the potential for dynamo-generated magnetospheres.”.

Earth’s magnetodynamo is generated in the convecting liquid iron outer core surrounding the solid iron inner core and is powered by the latent heat released during solidification of the iron.

With the prominence of iron in terrestrial planets, accurate and precise physical properties at extreme pressure and temperatures are required to predict what is happening within their interiors.

Through the experiments, the team determined the length of dynamo action during core solidification to the hexagonal close-packed structure within super-Earth exoplanets.

The team also obtained evidence that the kinetics of solidification at such extreme conditions are fast, taking only nanoseconds to transition from a liquid to a solid, allowing the team to observe the equilibrium phase boundary.

Reference: “Measuring the melting curve of iron at super-Earth core conditions” by Richard G.

Eggert, 13 January 2022, Science.

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