Auroras help scientists study energy instabilities in space

Scientists are using auroras to better understand the physics of explosive energy instabilities in space.

"An instability is a physical process whereby the energy output can essentially grow very quickly without limits," Colin Forsyth, physicist at the University College London's, told UPI in an email.

When a clean swell breaks and crashes on the beach, or when a pile of sand suddenly collapses, these are energy instabilities playing out in real time. Similar instabilities are happening throughout space, and auroras can help scientists track them down and study the physical processes that define them.

"The space around Earth is filled with electrons, protons and other electrically charged particles, constituting a plasma," Forsyth said. "Combined with the magnetic field from the Earth -- which extends out into space to form the magnetosphere -- this plasma can become energized. This energy build up can be unstable, and the plasma can then release this energy through different physical instabilities."

In their search for energy instabilities at the edges of space, scientists pointed their MOOSE camera -- short for Multi-spectral Observatory Of Sensitive EM-CCDs -- at a substorm brewing over Alaska.

Substorms are space weather events which, among other things, light up the the whole of the nightside auroral region for about an hour," Forsyth said. "They result from an energy build up in Earth's magnetosphere that itself is caused by Earth's magnetic field becoming linked to the magnetic field coming off the sun."

During substorms, energy builds up until it is released via instabilities, blasting electrons and protons into the upper atmosphere, energizing gas particles and causing them to glow vivid colors.

Forsyth and his colleagues were able to study this process in two new ways.

"The first was that we used data from an all-sky camera that was able to take scientific quality measurements of the aurora every 0.1 seconds and with a spatial resolution that is greater than before," he told UPI. "The second was the way in which the data was processed. Extracting the necessary information from the data required careful detection and tracking of an auroral arc."

The improved observations allowed scientists to more accurately characterize the electromagnetic waves that carry energized particles into the upper atmosphere. The data revealed a line of "auroral beads" traveling along an arc that grew in size and brightness.

Scientists were able to use the data to estimate the nature and origin of the instability in space. Forsyth and his colleagues described their work in a new paper published this week in the journal Nature Communications.

"The final piece of the puzzle was to develop the theory of these waves such that we could be sure they were the ones we thought they were -- the theory uses the conditions in space, which we can measure, to define the properties of the wave and the wave properties predicted by the theory matched our observations," Forsyth said.

Researchers hope to repeat their work using data collected by spacecraft traveling through Earth's magnetosphere. Scientists think their work could eventually be used to study energy instabilities far away from Earth.

"We are still trying to understand the whole implications of this work, but we see signs of similar instabilities on the sun and at the other planets in the solar system," Forsyth said. "Ultimately, this is a universal physical process and may even apply at more exotic objects such as exoplanets, brown dwarfs and other stars. The great thing about observing this process at Earth is that we actually go and measure it happening."

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San Antonio CA (SPX) Nov 16, 2018
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