Astronomers offer a new interpretation of the “dark finger-shaped voids” found in some solar flares

Published:

28 One 2022 20:25 GMT

Structures known as ‘supra-arcadian downflows’ by scientists were first discovered during 1999 sunlight, but have not been studied until now.

In January 1999, scientists discovered strange motions within the solar flare. Unlike conventional emissions that show bright energy emanating from our star, this phenomenon was presented Flow of downward movementAstronomers wondered exactly what they were seeing, describing the matter as “dark vacuums moving downwards” as matter fell towards the sun.

Now a team of researchers has come up with a new explanation for the unknown downward currents, called ‘by the scientific community’.supra-arcadian downhill flows‘(SAD). “We wanted to know how these structures are made.” He said Chengkai Shen, astronomer and principal author of research at the Harvard-Smithsonian Astronomical Center (CfA), Published This Thursday in the journal Nature Astronomy describes structures as “dark, finger-shaped elements”

“It’s like stretching a rubber band. “

Scientists believe that SADs have been linked to magnetic recombination since their discovery in the 1990s. The process occurs when the magnetic fields breakEmits very energetic, fast-moving radiation, and then reforms.

“In the sun, what happens is, you have a lot of magnetic fields in all directions. Eventually the magnetic fields combine to rebuild and release more energy in the form of sunlight,” Kathy explained. Reeves, astronomer CfA And co-author of the study. “It’s like stretching a rubber band And cut it in half. She’s depressed and stretched, so she’s going to break down. “

Researchers believe dark globes are signs of broken magnetic fields in the sun after a solar flare. However, they encountered a problem: most of the downward flows observed by scientists “Confusingly slowSaid Bin Chen, an astronomer at the New Jersey Institute of Technology.

According to Chengkai Shen, “This is not predicted by the classical reconnection models, which shows that downward flows must be very fast. This is a paradox that requires some other explanation.”

How are super-arcade downflows formed?

To find out what’s going on, the team examined images of the downsides taken by the Atmospheric Imaging Assembly (AIA) instrument at NASA’s Solar Dynamics Observatory Space Telescope. Takes pictures of our star every twelve seconds At seven different wavelengths of light to measure variations in the Sun’s atmosphere.

Next, the team operated 3D simulations of solar flares and compared them with observations. After all, the results revealed that most are flowing downwards Not generated by magnetic reconnection. Rather, they form on their own in turbulent environments and are the result of the interaction of two fluids of different densities.

Kathy Reeves points out that researchers see the same thing happening during the mixing of water and oil: two different liquid densities are unstable and ultimately separate. “Those dark, finger-shaped voids, Actually plasma-free. The density is much lower than the surrounding plasma, ”he said.

Now, the team plans to further explore the use of 3D simulations and processes to operate solar flares, which will help develop tools to predict space weather and minimize its impacts.

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