Astronomers Find First Radiation Belt Beyond Our Solar System

Astronomers Find First Radiation Belt Beyond Our Solar System
Astronomers Find First Radiation Belt Beyond Our Solar System - Artist's impression of aurora on brown dwarf LSR J1835+3259 and its surrounding radiation belt. Credits: Chuck Carter, Melodie Kao, Heising-Simons Foundation

For the first time, astronomers have found a radiation belt outside our solar system around the brown dwarf LSR J1835+3259. This belt, which is 10 million times denser than Jupiter's, is an important advance in the search for habitable and potentially Earth-sized planets. A network of 39 radio dishes spread around the world led to this finding.

A planet's radiation belts are ring-shaped magnetic formations surrounded by extremely high-energy electrons and charged particles.

All planets in the solar system with large-scale magnetic fields, including Earth, Jupiter, Saturn, Uranus, and Neptune, have radiation belts around Earth first observed in 1958 with the Explorer 1 and 3 satellites. However, no significant radiation belt has been detected outside of our solar system to date.

The first radiation belt outside of our solar system was discovered by Professor Evgenya Shkolnik of the School of Earth and Space Studies at Arizona State University and Melodie Kao, formerly of Arizona State University and now 51 Pegasi b Investigator at the University of California, Santa Cruz. It was found by a small group of astronomers, including The findings were published May 15 in the journal Nature.

The "brown dwarf" LSR J1835+3259, comparable in size to Jupiter but significantly denser, was the site of the find. Located 20 light-years away in the constellation Lyra, this object is too heavy to be a planet, but not heavy enough to be a star. It was unclear whether the radiation belts would be found around extraplanetary objects because they had never been clearly seen outside of our solar system before.

According to Shkolnik, who has spent many years researching the magnetic fields and habitability of exoplanets, “this is a critical first step towards finding many more such objects and improving our ability to search for smaller and smaller magnetospheres, and eventually allow us to study potentially habitable, Earth-sized planets. knows.”

The radiation belt this team found is a gigantic structure that cannot be detected by the human eye. Its brightest interiors are spaced 18 Jupiter diameters from its outer diameter, which is at least 9 Jupiter diameters wide. This newly discovered belt of extrasolar radiation is almost 10 million times more intense than Jupiter's, which is millions of times brighter than Earth's and exhibits the most energetic particles of any solar system planet. Jupiter's radiation belt consists of particles traveling near the speed of light and shines at the brightest radio wavelengths.

The team took three high-resolution images of radio-emitting electrons trapped in the magnetosphere of LSR J1835+3259 over the course of a year, using a now well-known observational method to detect our galaxy's black hole.

Scientists have deciphered the brown dwarf's dynamic magnetic environment known as the "magnetosphere", which has been observed for the first time outside the solar system, by coordinating 39 radio dishes stretching from Hawaii to Germany by creating an Earth-size telescope. They were even able to determine the shape of this magnetic field, which led them to the conclusion that it most likely had a dipole structure similar to that of Jupiter and Earth.

With the help of a network of radio dishes around the world, we can create exceptionally high-resolution photos to view things that no one has seen before. According to co-author Professor Jackie Villadsen of Bucknell University, "Viewing the top row of an eye map in California while standing in Washington, DC is comparable to our view.

But Kao and his group had early indications that they would discover a band of radiation surrounding this brown dwarf. Radio astronomers had already noted that LSR J2021+1835 emitted two types of observable radio emissions when the researchers made these measurements in 3259. Kao was a member of the team that six years ago determined that the source of the lighthouse-like and regularly flashing radio emission was the aurora.

However, LSR J1835+3259 also produced more consistent and weaker radio emissions. This information showed that these fainter emissions, very similar to Jupiter's radiation belts, could not actually be the result of stellar explosions.

According to the team's research, this phenomenon may be more common than previously thought and can be seen not only on planets, but also on brown dwarfs, low-mass stars, and perhaps even extremely high-mass stars.

The magnetosphere, including Earth, is the area around a planet's magnetic field and can shield the planet's atmosphere and surfaces from high-energy solar and cosmological particles.

In addition to factors such as the atmosphere and climate, Kao added, "things like the role of their magnetic field in maintaining a stable environment is something to consider when thinking about the habitability of exoplanets."

Their research revealed the difference between the lights of an aurora and the radiation belt from an object outside our solar system in terms of "shapes" and spatial position, in addition to the visible radiation belt.

“Auroras can be used to measure the strength of the magnetic field, but not its shape. According to Kao, this experiment was created to demonstrate a technique for determining the patterns of magnetic fields on brown dwarfs and eventually exoplanets. The 'courtyards' of the planets that make up our solar system can be compared in one example to radiation belts, but instead of flowers, energetic particles of the solar system emit light of various wavelengths and intensities.

The unique characteristics of each radiation belt reveal something about the energetic, magnetic and particle sources of that planet; its rotation speed, the strength of its magnetic field, its proximity to the Sun, whether it has moons that can produce additional particles or rings like Saturn's to absorb them, and more. We can now observe, for the first time, the types of "courtyards" that brown dwarfs and low-mass stars have. I look forward to the day when we can learn more about the magnetospheric houses of the outer planets.

source: scitechdaily

📩 23/05/2023 14:02