Astronomers using the Karl G. Jansky Very Large Array have observed long-lasting aurora-like radio bursts above sunspots. This discovery could help us better understand the behavior of our own star, as well as distant stars that emit similar radio emissions.
excellent other. We discovered radio bursts above sunspots that are similar to the radio emissions from the aurora borealis on Earth. The pink and purple stripes in this figure represent radio wave radiation, with high frequency radio signals near the sunspots, pink being high frequency and purple being low frequency radio signals. The thin lines represent the magnetic field lines above the sunspot. Sunspots are dark areas at the bottom of the sun. Image credit: Sijie Yu, New Jersey Institute of Technology.
“This sunspot's radio emission represents the first detection of its kind,” said Dr. Shijie Yu, an astronomer at the New Jersey Institute of Technology.
“Such radio bursts were detected about 40,000 kilometers (25,000 miles) above sunspots (relatively cool, dark, magnetically active regions of the Sun) that had previously been observed only on planets and other stars. It was done.”
On other planets like Earth, Jupiter, and Saturn, auroras sparkle in the night sky when solar particles get caught up in the planet's magnetic field and are pulled toward the poles where the magnetic field lines converge.
As the particles accelerate toward the poles, they generate powerful radio emissions at frequencies around a few hundred kilohertz that collide with atoms in the atmosphere and emit light as auroras.
The research team's analysis shows that radio bursts on sunspots likely occur in a similar way, when high-energy electrons are captured and accelerated by magnetic fields converging on sunspots. It suggests.
However, unlike Earth's aurora borealis, the radio bursts from sunspots occur at much higher frequencies, from hundreds of thousands of kilohertz to approximately one million kilohertz.
“This is a direct result of the sunspot's magnetic field being thousands of times stronger than Earth's magnetic field,” Yu says.
Similar radio emissions have been previously observed from several types of low-mass stars.
This discovery raises the possibility that auroral-like radio emissions originate from large spots on these stars, in addition to previously proposed polar auroras.
“This discovery excites us as it challenges existing concepts of solar radio phenomena and opens new avenues for exploring magnetic activity both in the Sun and in distant star systems. ” said Dr. Yu.
“NASA's ever-growing heliophysics fleet is well suited to continue investigating the source regions of these radio bursts,” said NASA Goddard Space Flight Center heliophysicist and solar radio researcher. said Dr. Nachimthuk Gopalswamy.
“For example, the Solar Dynamics Observatory continuously monitors the active regions of the Sun, which could be causing this phenomenon.”
In the meantime, the authors plan to review other solar radio bursts to see if any resemble the aurora-like radio bursts they discovered.
“We aim to determine whether some previously recorded solar outbursts may be examples of this newly identified emission,” Dr. Yu said.
of findings appear in the diary natural astronomy.
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S.Yu other. 2024. Long-lasting aurora-like radio emission detected over a sunspot. Nat Astron 8, 50-59; doi: 10.1038/s41550-023-02122-6
Source: www.sci.news
