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Physicists report clear evidence of how aurora is formed



Physicists report clear evidence of how aurora is formed

Physicists led by the University of Iowa report solid evidence that the aurora illuminating the sky at high latitudes is caused by electrons accelerated by powerful electromagnetic forces known as alfalfa waves. Credit: Austin. Montelius, University of Iowa

The aurora borealis, or northern lights, that fill the sky in high latitudes have fascinated people for millenia. But how it was created while the theory has not been conclusively proven.

In the new study A team of physicists led by the University of Iowa It reports conclusive evidence that the brightest aurora is produced by powerful electromagnetic waves during Earth̵

7;s magnetic storms. This phenomenon, known as Alfven waves, accelerates electrons toward Earth. This allows the particles to create a light show in a familiar atmosphere.

The study was published online June 7 in the journal nature communication, concludes a decades-long mission to demonstrate an experimental physical mechanism for electron acceleration by Alfven waves under conditions consistent with the Earth’s auroral magnetic field.

Greg Howes, associate professor at the department, said: “Measurements revealed that this small number of electrons passed through The ‘accelerated resonance’ by the Alfven wave electric field is similar to a surfer catching a wave and is continuously accelerated as the surfer moves with the wave. Physics and Astronomy at Iowa and co-authors

Scientists are well aware that energetic particles ejected from the Sun, such as electrons, travel at about 45 million miles per hour. Will precipitate along the Earth’s magnetic field into the upper atmosphere. by colliding with oxygen and nitrogen molecules This causes an excited state. These excited molecules relax by emitting light. causing the colorful shades of the aurora

This theory is supported by spacecraft missions, which often find Alfven waves moving toward Earth above the aurora. Probably accelerating electrons along the way. Space-based measurements support this theory, though. But the inherent limitations in spacecraft and rocket measurements prevent final testing.

Physicists were able to find corroborating evidence in a series of experiments conducted at the Large Plasma Device (LPD) in UCLA’s Basic Plasma Science Facility, a national collaborative research center supported by the Department of Energy and the US National Science Foundation.

“The idea that these waves can excite the electrons that create auroras goes back over four decades. But this is the first time we’ve been able to definitively confirm it works,” said Craig Kletzing, a professor of physics department. and astronomy at Iowa and study co-author. “These experiments led us to make important measurements that show that space measurements and theory help explain the key methods in truly creating aurora.”

The phenomenon of electrons “surfing” on a wave’s electric field is a theoretical process known as Landau Damping, first proposed by Russian physicist Lev Landau in 1946. Researchers have shown that the results agree. with a predicted signature for Landau damping.

The terms of experimentation, simulation and modeling provide the first direct evidence that Alfven waves can produce accelerated electrons. It creates aurora, said Troy Carter, professor of physics at UCLA and director of the UCLA Institute of Plasma Science and Technology.

“This challenging experiment required measuring a very small number of electrons descending from the LPD chamber at almost the same speed as the Alfven wave, less than one-thousandth of an electron in the plasma,” Carter said.


Catch a wave. Rockets shoot from the top of the world.


More information:
Physics measurement of an aurora-electron acceleration by Alfven waves. nature communication (2021). doi: 10.1038/s41467-021-23377-5 , www.nature.com/articles/s41467-021-23377-5.

Provided by the University of Iowa.



reference: Physicists Report Evidence of How Auroras Are Created (2021, June 7) Retrieved 7 June 2021 from https://phys.org/news/2021-06-physicists-definitive. -evidence-auroras.html

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