Tiny 'Nanoflares' May Solve Sun Mystery
Scientists have found that the sun's outer atmosphere, or corona, can reach temperatures 1,000 times higher than those at the surface of the star, but solar physicists previously had no explanation for why this temperature discrepancy is so great. Now, researchers think the relatively tiny flares may be the "smoking gun" that explains this mysterious cosmic occurrence.
The new study provides the first direct proof that nanoflares keep the sun's corona at a temperature of millions of degrees, far hotter than the sun's visible surface, which is about 6,000 degrees Kelvin (10,000 degrees Fahrenheit). [The Biggest Solar Flares of 2014: Photos]
"The nanoflare model has been around for a while," said Jeffrey Brosius, a solar physicist at NASA's Goddard Space Flight Center in Greenbelt, Maryland "With better instrumentation, we were hoping to find the evidence that was predicted by the model."
Nanoflares happen because of huge magnetic fields located throughout the sun's corona. These loops are anchored in the photosphere, the sun's visible surface, but move around due to turbulence in the photosphere. Sometimes the field lines cross, and they become twisted and tangled.
When this happens in the presence of plasma, current sheets form, and the "stress" builds until the magnetic field "breaks," releasing lots of energy very quickly. This kind of crossing of magnetic fields can happen thousands of times a second over the whole solar surface, and this transfers energy to the plasma in the corona. That energy transfer could explain the corona's extra heat.
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Scientists have recently gathered some of the strongest evidence to date to explain what makes the sun's outer atmosphere so much hotter than its surface. The new observations of the small-scale extremely hot temperatures are consistent with only one current theory: something called nanoflares -- a constant peppering of impulsive bursts of...
You'd think that the sun's surface would be hotter than its outer atmosphere, but that's not the case. In fact, it's a phenomenon that has puzzled scientists for decades. Now, they may have the answer new observations reveal that it may have something to do with nanoflares. NASA's Solar Dynamics Observatory captured this image of what the sun...
( via space.com )
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