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Definition: | Electromagnetic waves that are propagated along lines of magnetic force in a plasma. Alfen waves, named after plasma physicist and Nobel Prize winner Hannes Alfen, have frequencies significantly less than the ion cyclotron frequency, and are characterized by the fact that the magnetic field lines oscillate with the plasma. |
Sun's Magnetic Secret Revealed
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By Jeremy Hsu Powerful magnetic waves have been confirmed for the first time as major players in the process that makes the sun's atmosphere strangely hundreds of times hotter than its already superhot surface. The magnetic waves called Alfven waves can carry enough energy from the sun's active surface to heat its atmosphere, or corona. "The surface and corona are chock full of these things, and they're very energetic," said Bart de Pontieu, a physicist at the Lockheed Martin Solar and Astrophysics Laboratory in California. The sun contains powerful heating and magnetic forces which drive the temperature to tens of thousands of degrees at the surface yet the quieter corona wreathing the sun reaches temperatures of millions of degrees. Scientists have speculated that Alfven waves act as energy conveyor belts to heat the sun's atmosphere, but lacked the observational evidence to prove their theories.
Staff Writer
posted: 22 January 2008
06:04 am ET
I read that article. I was surprised that the Alfven wave propagation speed was so slow. I’ll have to look into that more sometime.
By the way, I am very comfortable with journalists talking about these energies in terms of A-Bombs. I just wish that they would say something like “10kt”, or “Hiroshima” or “5 Megaton” when they use use it. Used as in this article, there is a 4-orders-of-magnitude range possible - a bit too big for useful information even in most non-technical articles.