The waves that are created as the solar wind hits Earth’s magnetic field seem to escape the turbulent region around our planet, but how they do this has remained a mystery.
Now, a research team has discovered how these waves appear to be alive: They continue past the leading ‘shock’ region into a region called ‘shock’ and then create ‘clone’ waves with identical qualities, thus explaining how they seem to cross this region in the near-a land Void. Therefore, what astronomers had been observing for decades were not the waves created by the solar wind but rather the newly produced “clones” of the waves.
“How waves survive through shock has remained a mystery since waves were first discovered in the 1970s,” said Lucille Turk, an academic research fellow at the University of Helsinki in Finland and lead author of the study. statment. “No evidence of those waves was found on the other side of the shockwave.”
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The magnetosphere is a magnetic bubble that protects the Earth from charged particles the sun Call solar wind By directing these particles down the magnetic field lines and to the other side of our planet. The interaction between the supersonic solar wind and the Earth’s magnetic field creates the shock zone, also known as the bow shock. The tremor then forms the “upstream” of this shock zone.
The influence of the solar wind causes electromagnetic waves to appear as tiny oscillations Earth’s magnetic field. Waves with the same vibrations as waves have been detected in this shock region on the sunward side of Earth, indicating that they can enter the magnetosphere and travel all the way to the planet’s surface. But how can these waves cross the violent shock zone and remain unchanged?
Türk and his colleagues have been studying propagating waves in the emanation region for three years, and are turning to a computer model called the Vlasiator to recreate and understand the physical processes that play a role in wave transmission. By studying simulations provided by the Vlasiator, a system developed at the University of Helsinki by research led by Minna Palmroth, the team found waves on the other side of the shock zone that had properties that were nearly identical to those of the previous tremor. space.
They followed this discovery by looking for signatures of these waves in the satellite data and confirmed that the simulation was correct. But they still suspected that the waves could cross the shockwave and travel to Earth.
“At first, we thought the initial theory proposed in the 1970s was correct: waves can pass through shock without change,” Turk said. “But there was a discrepancy in wave properties that this theory couldn’t reconcile, so we dug further. In the end, it became clear that things were more complicated than they seemed.
“The waves we saw behind the shock were not the same as those in the frontal shock, but new waves created at the shock from the periodic impact of the shock waves,” Turk said.
The team believes that when the solar wind flows through the shock, it compresses and heats it, with the force of the shock determining how far this happens. The peaks and troughs of the waves coming from the foreground shock “tunes” the shock as it reaches it and causes it to alternate between weak and cyclically strong space weather. This then creates new shock waves which are thus aligned with the shock waves. Vlasiator simulations suggested that these waves should only be detected in a narrow region behind the shock and that they could easily be hidden by disturbances in this region. This may explain why these waves were not observed before.
The team’s research is published Dec. 19 in the journal Nature nature physics (Opens in a new tab).
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