2023-05-22 09:45:16
Earth’s radiation belts, known as the Van Allen belts, are large donut-shaped zones of high-energy particles captured from the solar winds by Earth’s magnetic field. Jupiter’s radiation belts are also famous. Now, astronomers have observed, for the first time, a radiation belt or set of belts of this type outside the solar system.
The first radiation belts to be discovered were those surrounding the Earth. The finding was made in 1958, using the Explorer 1 and Explorer 3 satellites. Since then, radiation belts have become a well-known feature on planets in our solar system: all planets with large-scale magnetic fields (including Earth , Jupiter, Saturn, Uranus and Neptune) have them. However, until now no such radiation belt has been clearly seen outside our solar system.
A team of astronomers, led by Melodie Kao, from Arizona State University and now from the University of California at Santa Cruz, both institutions in the United States, have discovered the first such radiation belt outside our solar system.
The discovery has been made around the brown dwarf LSR J1835+3259, which is about the same size as Jupiter but much denser. Lying just 20 light-years away in the constellation Lyra, it is not massive enough to be a star, and not massive enough to be a proper planet. Stars of this class are called brown dwarfs. Until now, the radiation belts have never been clearly visible outside of our solar system. Furthermore, it was unknown whether they could exist around objects other than planets.
Artist’s impression of an aurora and the radiation belt of the brown dwarf LSR J1835+3259. (Illustration: Chuck Carter, Melodie Kao, Heising-Simons Foundation)
The now discovered radiation belt is a gigantic structure. Its outer diameter spans at least 18 Jupiter diameters. Made up of particles traveling near the speed of light and brightest at radio wavelengths, this newly discovered extrasolar radiation belt is nearly 10 million times more intense than Jupiter’s cluster of belts, which time is millions of times brighter than Earth’s.
The study is titled “Resolved imaging confirms a radiation belt around an ultracool dwarf”. And it has been published in the academic journal Nature. (Fountain: NCYT de Amazings)
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