Strange things happen inside planets, where familiar materials are subjected to extreme pressure and heat.
Iron atoms most likely danced in Earth’s dense core, and hot, heavy black ice – both solid and liquid – most likely formed in the water-rich gas giants of Uranus and Neptune.
Five years ago, scientists recreated this strange ice, called superionic ice, for the first time in a laboratory experiment; Four years ago, they confirmed its existence and crystal structure.
Then last year, researchers at several US universities and the Stanford Linear Accelerator Center Laboratory in California (SLAC) discovered a new phase of super-ionized ice.
Their discovery deepens our understanding of why such things exist on Uranus and Neptune The magnetic field is outside the filter range With multiple electrodes.
From our terrestrial environment, you would be forgiven for thinking that water is a simple, elbow-shaped molecule consisting of one oxygen atom bonded to two hydrogen atoms that stay in fixed positions when water freezes.
It’s super Surprisingly different, but perhaps somewhere in between The most abundant form water in the universe – perhaps not only filling the interior of Uranus and Neptune, but also similar outer planets.
These planets have extreme pressures of two million times the pressure of Earth’s atmosphere, and their interiors are as hot as the surface of the Sun, making water strange.
In 2019, scientists confirmed what physicists had already confirmed Expected in 1988: A structure in which oxygen atoms in superionized ice are trapped in a dense cubic lattice, while ionized hydrogen atoms are released, flowing through the lattice like electrons through metal.
This gives superionic ice conductive properties. This is too This increases its melting point So that frozen water remains solid at high temperatures.
In this latest study, physicist Arianna Gleason of Stanford University and her colleagues bombarded a thin layer of water, sandwiched between two layers of diamond, with an extremely powerful laser.
Successive shock waves increased the pressure to 200 gigapascals (2 million atmospheres) and the temperature to about 5,000 K (8,500 degrees Fahrenheit) – hotter than the temperature of the 2019 experiment, but at a lower pressure.
“The recent discovery of water-rich Neptune-like exoplanets requires a more detailed understanding of planetary phase diagrams. [water] “At pressure and temperature conditions relevant to their planetary interiors,” said Gleason and colleagues explained in their paperstarting January 2022.
X-ray diffraction then revealed the hot, dense structure of ice crystals, even though the pressure and temperature conditions were maintained for only a fraction of a second.
The resulting diffraction pattern confirms that the ice crystals are actually a new phase that is different from the superionized ice observed in 2019. The newly discovered superionized ice, Ice The cubic structure is body-centered And improved conductivity compared to its predecessor from 2019, the Ice XVIII.
Conductivity is important here because moving charged particles produce a magnetic field. This is the basics Dynamo theorieswhich describes how conductive fluids, such as the Earth’s mantle or inside other celestial bodies, give rise to magnetic fields.
If more of the interior of a Neptune-like ice giant was sucked in by soft solids, and less was sucked in by rotating fluid, then it would Change the type of magnetic field produced.
If the planet contains two superionization layers with different conductivities towards its core, as Gleason and colleagues say Recommend Neptune might have one, and then the magnetic fields generated by the outer liquid layers would interact with each of them differently, making things even weirder.
Neptune’s internal structure consists of two layers of superionized solid ice (ice 19 is blue, ice 18 is green) beneath a layer of ionic liquid that is thought to generate the planet’s magnetic field. (Gleeson et al., Scientific report2023)
Gleason and co We conclude Increased conductivity of superionized ice layers similar to Ice XIX would encourage the formation of unstable multipolar magnetic fields like those emitted by Uranus and Neptune.
If so, it would be a satisfying result more than 30 years after NASA’s Voyager 2 space probe, launched in 1977, flew by Earth. Our solar system has two Ice giant And measurement their very unusual magnetic field.
This study was published in Scientific report.
2023-10-15 05:15:39
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