‘Claws of Chaos’ appear in hot Jupiter planets

Hot Jupiters (HJs) are some of the most extreme planets known to exist in the universe. With a size close to the planet Jupiter and in very close proximity to its host star — an HJ’s orbital radius is about 5% that of Earth’s — HJs have enormous differences in temperature between their perpetual day and night sides, causing strong winds between the hemispheres.

This leads to extraordinary thermal effects. High temperatures ionize the alkali metals known to exist in HJ atmospheres, eventually leading to a self-sustaining positive feedback loop from their interaction with the global magnetic field of the planet, creating a thermoresistive instability (TRI). Hardy et al. modeled HJ atmospheres to understand TRIs, their trigger, and their decay.

They found that TRIs occur at irregular periods in some areas of parameter space. When the timing between TRI bursts is just right, subsequent TRIs can occur before the previous one has fully decayed, and the process becomes chaotic.

The dramatic rise in temperature in an HJ’s atmosphere associated with a TRI can increase the planet’s luminosity enough to be observed with the latest generation of telescopes, such as the James Webb Space Telescope. However, when TRI dynamics are chaotic, they are difficult to predict, and thus, difficult to observe.

An example the researchers call “The Claws of Chaos” epitomizes the work. In this representation, as they increased its resolution, more and more chaotic, clawlike structures and fractals appeared.

“In the end, The Claws are a good analogy for this simple model: The more we look into it, the more complex it is,” said author Raphaël Hardy.

Source: “Magnetohydrodynamical thermoresistive instability and the claws of chaos,” by Raphaël Hardy, Paul Charbonneau, Andrew Cumming, Chaos (2025). The article can be accessed at https://doi.org/10.1063/5.0245096 .