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'MRI' of Sun's Activity Shows Surprisingly Slow Plasma Waves


This 3D image of the Sun shows the active surface and sunspots fueled by plasma waves. Researchers took an 'MRI' of the Sun and found that the convection within our star is moving 100 times slower than we thought.
(Photo: Credit: NASA)

By Chelsea Whyte | July 9, 2012 10:38 PM EDT

The heart of the Sun's activity is made up of circulating plasma at its interior, and a kind of doctor's checkup reveals that our star's lifeblood is pumping at a much slower rate than previously thought.

A team of scientists from New York University, Princeton University, the Max Planck Institute, and NASA used high-resolution imaging to piece together a kind of 'MRI' of the Sun's inner-workings and found that the flowing plasma that fuels the star is moving 100 times slower than they expected.

The results may mean scientists will "need to overhaul our understanding of the physics of the sun's interior," said Shravan Hanasoge, an associate research scholar in geosciences at Princeton University and a visiting scholar at NYU's Courant Institute of Mathematical Sciences, according to The Huffington Post [ http://www.huffingtonpost.com/2012/07/09/sun-mri-plasma-star_n_1659697.html ].

The findings, published in the scientific journal Proceedings of the National Academy of Sciences, change our notions of the way the Sun is heated. Beginning with nuclear fusion at the core of the star, heat is transported to the surface of the Sun by convection, producing waves of extremely hot ionized gas called plasma.

The interior motion of plasma affects the creation of sunspots and the Sun's magnetic fields.

"Our current theoretical understanding of magnetic field generation in the Sun relies on these motions being of a certain magnitude," explained Shravan Hanasoge, an associate research scholar in geosciences at Princeton University and a visiting scholar at NYU's Courant Institute of Mathematical Sciences. "These convective motions are currently believed to prop up large-scale circulations in the outer third of the Sun that generate magnetic fields."

In order to get a look inside the process of the circulating plasma flows, the researchers used images from a 16-million pixel camera on the Helioseismic and Magnetic Imager on board NASA's Solar Dynamics Observatory.

Capturing the precise surface movements of these waves allowed the scientists to calculate the speed of the underlying motion.

"Our results suggest that convective motions in the Sun are nearly 100 times smaller than these current theoretical expectations," said Hanasoge, according to UPI [ http://www.upi.com/Science_News/2012/07/09/Scientists-create-MRI-of-suns-interior/UPI-91761341884824/ ]. "If these motions are indeed that slow in the Sun, then the most widely accepted theory concerning the generation of solar magnetic field is broken, leaving us with no compelling theory to explain its generation of magnetic fields and the need to overhaul our understanding of the physics of the Sun's interior."

© 2012 iScience Times

http://www.isciencetimes.com/articles/3380/20120709/mri-suns-activity-shows-surprisingly-slow-plasma.htm [with comment]


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Inside The Sun

Published on Jul 9, 2012 by HuffPostScienceYT

This simulation, provided to HuffPost Science by New York University, shows radially directed flows from the ASH (anelastic spherical harmonic) numerical simulations at a depth of approximately 14,000 km from the surface of the Sun.

Courtesy Mark Miesch; from Miesch, Brun, DeRosa & Toomre, Astrophysical Journal 2008 [an example of a simulation undercut by the new 'MRI' finding]

http://www.youtube.com/watch?v=9L00JE1NSnA (emphasis added)


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