A different picture of the interior of the sun

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Friday, September 5, 2014

New observational work provides more information about the evolution of the Sun's interior and origins of its enigmatic 11(-ish) solar cycle. The research potentially opens the door to improved forecasting of decadal-scale solar variability.

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Bands of magnetized solar material – with alternating south and north polarity – march toward the sun's equator. Comparing the evolution of the bands with the sunspot number in each hemisphere over time may change the way we think about what's driving the sun's 11-year sunspot cycle. Image Credit: S. McIntosh

Historically, theories about what's going on inside the sun to drive the solar cycle have relied on only one set of observations: the detection of sunspots, a data record that goes back centuries. Over the past few decades, realizing that sunspots are areas of intense magnetic fields, researchers have also been able to include observations of magnetic measurements of the sun from more than 90 million miles away.

"Sunspots have been the perennial marker for understanding the mechanisms that rule the sun's interior," said Scott McIntosh, a space scientist at the National Center for Atmospheric Research in Boulder, Colorado, and first author of a paper on these results that appears in the September 1, 2014, issue of the Astrophysical Journal. "But the processes that make sunspots are not well understood, and far less, those that govern their migration and what drives their movement. Now we can see there are bright points in the solar atmosphere, which act like buoys anchored to what's going on much deeper down. They help us develop a different picture of the interior of the sun."

McIntosh explains that a complex interaction of magnetic field lines may take place in the sun’s interior that is largely hidden from view. The recent observations suggest that the sun is populated with bands of differently polarized magnetic material that, once they form, steadily move toward the equator from high latitudes. These bands will either have a northern or southern magnetic polarity and their sign alternates in each hemisphere such that the polarities always cancel. For example, looking at the sun’s northern hemisphere, the band closest to the equator – perhaps of northern polarity – would have magnetic field lines that connect it to another band, at higher latitudes, of southern polarity. Across the equator, in the bottom half of the sun, a similar process occurs, but the bands would be an almost mirror image of those across the equator, southern polarity near the equator and northern at higher latitudes. Magnetic field lines would connect the four bands; inside each hemisphere and across the equator as well.

Researchers Discover New Clues to Determining the Solar Cycle