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Nancy Neal/Don Savage
Headquarters, Washington
(Phone: 202/358-1547)

Lindsay Renick Mayer/Bill Steigerwald
Goddard Space Flight Center, Greenbelt, Md.
(Phone: 301/286-8955)

December 8, 2003
 
RELEASE : 03-398
 
 
Sun's Power & Violence Revealed At AGU
 
 
New discoveries about the elusive rules governing the sun's most violent phenomena will be presented at 6 p.m. EST today at a press conference during the annual American Geophysical Union Fall Meeting in San Francisco.

A team of solar scientists led by Dr. James Chen of the Naval Research Laboratory has confirmed the basic anatomy of massive solar eruptions called Coronal Mass Ejections (CMEs) is a twisted magnetic structure called a "magnetic flux rope," as first hypothesized over 10 years ago.

A team, led by Dr. Jiong Qiu of the Center for Solar Research at the New Jersey Institute of Technology, found a close relationship between the rate of the release of magnetic energy, called "magnetic reconnection," during solar flares and the acceleration of CMEs.

CMEs are billion-ton eruptions of electrically charged-gas (plasma) in the sun's atmosphere (corona). The fastest CMEs are blasted into space at a speed of up to five million miles per hour (eight million km/hr). Solar flares are giant explosions that spew radiation and result in the heating of solar gas and the acceleration of particles to nearly the speed of light.

Magnetic reconnection is the twisting and snapping of invisible magnetic field lines on the sun. When these fields snap from buildup of magnetic energy, plasma is heated and particles are accelerated, resulting in an eruption. According to Dr. Qui's research, the eruptions speed up and slow down in correlation with the reconnection rate. The magnetic reconnection may then create and help maintain a "magnetic flux rope" which, according to Dr. Chen, is present at the earliest stages of the CME process.

Flux ropes are twisted or curved magnetic currents that run through the sun's ionized gas, similar to electricity running through the copper wires of a house. Much like pushing the center of a slinky away from you while holding one end in each hand, if the current is large enough, the flux rope will expand outward and become more curved. If the center erupts and expands away from the sun, it may encounter the Earth's magnetic field (magnetosphere), transferring magnetic energy and resulting in large electric currents. These currents can shut down electrical systems on Earth and disrupt signals from satellites and aircraft.

"The most basic unanswered question regarding flux rope models is how and when the magnetic field passing through the area becomes highly-energetic," said Dr. Gareth Lawrence, a solar scientist at NASA's Goddard Space Flight Center, Greenbelt, Md. who will help present this research at the AGU Fall Meeting. "If we can answer that, maybe we can figure out how to predict when and where a flux rope will strike the magnetosphere. Better space weather prediction means more reliable communications, power transmissions, and other large-scale electromagnetic technologies. These are all in the public interest," she added.

Numerous space-based and ground-based observatories contributed to the research Lawrence will present. The space-based observatories include NASA's Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI); NASA's Transition Region and Coronal Explorer (TRACE); and ESA's Solar Heliospheric Observatory (SOHO). Ground-based observatories include the Big Bear Solar Observatory and the Owens Valley Solar Array.

For information about NASA on the Internet, visit:

http://www.nasa.gov

 

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