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Sun’s rotation driven by enormous plasma flows

Observations of giant structures support long-theorized heat transport mechanism

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2:29pm, December 5, 2013

BIG SOLAR CELLS  Giant, long-lived convective structures (left) move plasma on the sun’s surface. Earlier observations found only much smaller plasma flows covering the sun (right). In these illustrations, blue indicates plasma flowing east to west; red indicates west to east.

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Massive, long-lasting plasma flows 15 times the diameter of Earth transport heat from the sun’s depths to its surface, according to a study in the Dec. 6 Science. The finding supports a decades-old explanation of why the sun rotates fastest at its equator.

In the outermost 30 percent of the sun, known as the convective zone, rising plasma carries heat generated by nuclear fusion in the sun’s guts. Once at the surface, much of the plasma’s energy radiates into space; the cooler, denser plasma then sinks, driving further convection and creating circulating loops called convection cells. Some especially massive convective structures, called supergranules, can last up to 24 hours and have diameters greater than Earth’s.

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