December 11, 2023


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Researchers see “aurora” above sunspots

Researchers see “aurora” above sunspots

The radio emissions detected about 24,855 miles (40,000 kilometers) above the sun’s dark zone have aurora-like qualities, according to a team of astronomers who studied the emissions.

The emissions were seen above sunspots, a dark area on the sun’s surface. The magnetic fields around sunspots are about 2,500 times stronger than those on Earth. According to the National Weather ServiceThis makes the temperature in sunspots cooler than the brighter parts of our star’s surface.

Radiowave emissions were detected by the Jansky Very Large Array in April 2016, but only now has the research team reported its analysis of the data. The team described the emissions as “aurora-like” based on their spectra, polarization and duration, among other factors. It was a team analysis published This week in Nature astronomy.

“We detected a strange type of long-duration polarized radio bursts emanating from sunspots, which lasted for more than a week,” said Siji Yu, an astronomer at the New Jersey Institute of Technology’s Center for Solar and Terrestrial Research (NJIT-CSTR). ) and the lead author of the study at an institute launch. “This is very different from typical, transient solar radio bursts that typically last minutes or hours. It is an exciting discovery and has the potential to change our understanding of stellar magnetic processes.”

Auroras on Earth occur when charged particles from the Sun come into contact with the Earth’s atmosphere and magnetic field. Then the gases in our atmosphere glow: oxygen in red and the familiar green aurora, nitrogen in blue and purple, According to NASA.

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“Unlike Earth’s aurora, sunspot aurora emissions occur at frequencies ranging from hundreds of thousands of kilohertz to nearly a million kilohertz — a direct result of the sunspot’s magnetic field being thousands of times stronger than Earth’s magnetic field,” Yu added.

But Earth is unique in its twilight. last year, Photographed by the Webb Space Telescope The auroral regions at Jupiter’s poles glow bright blue in the Near Infrared Camera (NIRCam) view. Just last month, the Keck II telescope’s near-infrared spectrometer (NIRSPEC) was used Observed infrared aurora on the edges of Uranusin addition to the already known ultraviolet aurora that sometimes glows above the planet.

Researchers do not believe that sunspot radio emissions are related to the timing of solar flares; Instead, they hypothesize that occasional flares feed electrons into magnetic field loops that stop at sunspots. The team also believes that other stars could boast similar “sunspot radio afterglows.”

“By understanding these signals from our Sun, we can better explain the powerful emissions from the most common types of stars in the universe, M dwarf stars, which may reveal links to Fundamental to astrophysical phenomena. CSTR and co-author of the paper, in the same issue.

Combined with ground-based observations such as those made by the Very Large Array, spacecraft can help elucidate the dynamics at play on the Sun’s surface. NASA Solar Orbiter It flies straight through a coronal mass ejectiongiving researchers insights into the nature of storms, and this was done by the agency’s Parker Solar Probe Even immersed in the sun’s corona.

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Although our Sun has powered life on Earth for billions of years, it still hides some secrets from us. Fortunately, we are slowly improving our understanding of our local star, our raison d’être.

more: How do we know when the sun will die?