Team unravels sunspot mystery

Thomas

n what may be one of the most important steps in understanding sunspots since they were discovered by Chinese sky watchers more than two millennia ago, researchers at Rochester, along with researchers at the University of Colorado, University of Cambridge, and University of Leeds, have reported an answer to several sunspot mysteries in the current issue of Nature.

With the help of sophisticated computer models and data from solar telescopes that give spectacular views of the sun, the team has discovered that the lines of magnetic force that surge out of sunspots appear to peel apart like husks off an ear of corn as some of the lines are dragged back beneath the surface by a sort of solar quicksand.

This "quicksand" and the magnetic fields it bends create the penumbrae, the strange rings of mid-darkness around some sunspots that have eluded explanation by astronomers since Galileo first sketched them.

"We believe we have found the key to understanding the structure of sunspots," says John Thomas, professor of mechanical and aerospace sciences and of astronomy. "It's the missing link of sunspot evolution--explaining why the main magnetic tube gets torn apart like a peeled banana, why some lines of force dive back below the surface of the sun, and why sunspots grow a penumbra in the first place."

The team tackled the problem from a theoretical perspective using sophisticated computer simulations of the surface layers of the sun, and the results show a sort of magnetic quicksand lurking along the surface of the sun.

This research was funded by NASA, the United Kingdom Particle Physics and Astrophysics Research Council, and the Nuffield Foundation.

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