New theoretical model can help us understand what’s inside the ice giants

Hyperaxion Aug 16, 2020

Extreme temperature and pressure conditions have a direct impact on H2O molecules, causing them to assume a phase known as superionic water.

Scientists at Scuola Internazionale Superiore di Studi Avanzati, in Italy, and at the University of California, have developed a method that will help us understand the interior of the planets Uranus and Neptune, the ice giants of the Solar System.

New theoretical model can help us understand what's inside the ice giants
(Credit: Federico Grasselli).

The research, published in July in the journal Nature Communications, was based on computer simulations of the water present on these planets.

What is known about the interior of a planet is based on the characteristics of its surface and its magnetic field, which are influenced by the physical properties of its internal structure.

So, the researchers tried to assess the conduction of electricity and heat in water under extreme conditions of temperature and pressure, such as those found in ice giants and some exoplanets.

“We have developed a theoretical and computational method to compute the thermal and electrical conductivity of water, in the phases and conditions occurring in such celestial bodies,” explained Federico Grasselli and Stefano Baroni, co-authors of the study.

The model was created from simulations of the microscopic dynamics of atoms and took into account the quantum nature of electrons.

According to the scientists, “by simulating the atomic scale for fractions of a nanosecond, we are able to understand what has happened to enormous masses on time scales of billions of years.”

Alien water

Scientists considered water in solid and liquid states, but also in its superionic – or alien – version, as it was called.

This phase only exists under extreme temperature and pressure, which cause water molecules to dissociate into atoms with positive and negative electrical charges (ions).

“Superionic water lies somewhere between the liquid and solid phases,” Grasselli and Baroni said. “The oxygen atoms in the H2O molecule are organized in a crystalline network, while the hydrogen atoms diffuse freely as in a charged fluid.”

“Superionic water lies somewhere between the liquid and solid phases,” the researchers said. “The oxygen atoms of the H2O molecule are organised in a crystalline lattice, while hydrogen atoms diffuse freely like in a charged fluid.”

So, with the exotic physical properties of Uranus and Neptune in mind, the researchers found it crucial to consider the presence of superionic water in the ice giants – and it worked.

According to them, the simulations show that the electrical conductivity of superionic water is much higher than previously believed, which directly impacts the current models of the magnetic fields of these planets.

Furthermore, thanks to the new method, scientists were able to hypothesize that a frozen core in Uranus would explain the unusually low luminosity of the planet. “[There may be] an extremely low heat flux from its interior towards the surface,” they said.

Related topics:

Ice giants Neptune Uranus

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