Researchers and collaborators at Lawrence Livermore National Laboratory (LLNL) at the University of California, USA, used lasers to analyze iron within exoplanets. The simulator served as a basis for the experimental determination of 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 the Earth’s inner core and nearly four times the pressure of any previous experiment.
Artist’s impression of a cross-section of the super-Earth with the mantle-mounted NIF target camera, looking into the heart. Credit: John Jett/LLNL.
According to the study published in
no science, many experiments have been conducted that simulate conditions that see a speck of iron descending toward the center of a super-Earth core – the name by which any exoplanet has a mass greater than Earth but less than Earth than the gas giants known in the solar system.
The experiments were awarded under the National Ignition Facility (NIF) Science Discovery Program, which is publicly available and available to all researchers.
“The richness of iron within rocky planets makes it imperative to understand the properties of iron and its response to extreme conditions in the cores of more massive Earth-like planets,” said Rick Krause, a physicist at LLNL and lead author of the article. . “The melting curve of iron is essential for understanding the internal structure, thermal evolution, as well as the potential of dynamo-generated magnetospheres.”
Super-Earth exoplanets experience high pressure and temperature
The magnetosphere is believed to be an important component of habitable terrestrial planets, such as Earth. Earth’s magnetodynamics is generated in the outer core of liquid iron wrapped around the inner core of solid iron and powered by the latent heat released when the metal solidifies.
With the prominence of iron on terrestrial planets, physical properties resistant to extreme pressure and temperature are essential to predicting what happens within the inner planets.
The property of iron of the first order is its melting point, which is still a matter of debate about the conditions inside the Earth. The melting curve is the largest rheological transition that a substance can go through, from one resistant substance to another without it. This is where a solid turns into a liquid, and the temperature depends on the pressure of the iron.
Through experiments, the team determined how long the dynamo would run as the core of the hexagonal structure tightly solidified in the super-Earths’ exoplanets.
“We found that terrestrial exoplanets four to six times the mass of Earth would have the longest dynamo, providing a significant shield from cosmic radiation,” Krause said.
“In addition to our interest in understanding the habitability of exoplanets, the technology we developed for iron will be applied in the future to more programmatically related materials, including inventory management software,” he said.
According to Cross, the melting curve is an incredibly sensitive constraint on the state model equation. The team also obtained evidence that the kinetics of solidification under these extreme conditions is rapid, taking only nanoseconds to go from a liquid state to a solid state, allowing the team to observe phase boundaries from equilibrium.
“This demo improves time-dependent material response modeling for all subjects,” Krause said.
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