Sun's Power & Violence Revealed at AGU

Nancy Neal/Don Savage
Headquarters, Washington December 8, 2003
(Phone: 202/358-1547)

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

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 Library 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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