Spiral Superionic Carbon Hydride: A Strange New State of Matter Inside Uranus and Neptune

Something unusual may be happening to matter deep inside Uranus and Neptune. New simulations suggest that carbon hydride (CH) could form a strange superionic state under extreme conditions.

Interest in planetary interiors has grown as more than 6,000 exoplanets have been discovered. Researchers are trying to understand how planets form and evolve by combining observations, experiments, and simulations, especially regarding magnetic field generation, as seen in studies like those from the JWST.

Uranus and Neptune contain layers of “hot ices” beneath their outer atmospheres, made of water, methane, and ammonia. Under extreme pressure and heat, these compounds behave in unfamiliar ways.

Simulating Extreme Conditions Inside Ice Giants

Cong Liu and Ronald Cohen conducted detailed quantum simulations using high-performance computing and machine learning. Their study, published in Nature Communications, tested pressures between 500 and 3,000 gigapascals and temperatures from 4,000 to 6,000 Kelvin.

They focused on carbon hydride (CH), a simple mix of carbon and hydrogen commonly found in planetary interiors. Under these conditions, the material exhibited behaviors not seen on Earth.

A Spiral Superionic State

The simulations revealed a quasi-one-dimensional superionic state. In this phase, carbon atoms form a stable framework, while hydrogen atoms move through it along spiral, helical paths.

“This newly predicted carbon-hydrogen phase is particularly striking because the atomic motion is not fully three-dimensional. Instead, hydrogen moves preferentially along well-defined helical pathways embedded within an ordered carbon structure.”

Ronald Cohen

Superionic states behave partly like solids and partly like liquids. Here, hydrogen motion is directional and controlled.

Implications for Planetary Magnetic Fields

This movement could influence how heat and electricity are transported, which is linked to magnetic field generation, much like advanced space telescope observations of cosmic phenomena.

Uranus and Neptune have unusually shaped magnetic fields. A layer with this directional behavior could help explain them. Such insights align with ongoing missions like the ESA Space Rider.

“Carbon and hydrogen are among the most abundant elements in planetary materials, yet their combined behavior at giant-planet conditions remains far from fully understood.”

Cong Liu

These findings demonstrate that even simple elements can behave unexpectedly under extreme conditions.