Featured Research

from universities, journals, and other organizations

New Theory Unravels Magnetic Instability

Date:
December 11, 2002
Source:
Los Alamos National Laboratory
Summary:
Reconnection, the merging of magnetic field lines of opposite polarity near the surface of the sun, Earth and some black holes, is believed to be the root cause of many spectacular astronomical events such as solar flares and coronal mass ejections, but the reason for this is not well understood. Researchers at Los Alamos National Laboratory now have a new theory that may explain the instability and advance the understanding of these phenomena.

LOS ALAMOS, N.M., Dec. 6, 2002 - Reconnection, the merging of magnetic field lines of opposite polarity near the surface of the sun, Earth and some black holes, is believed to be the root cause of many spectacular astronomical events such as solar flares and coronal mass ejections, but the reason for this is not well understood. Researchers at Los Alamos National Laboratory now have a new theory that may explain the instability and advance the understanding of these phenomena.

Theorists Giovanni Lapenta of Los Alamos National Laboratory's Plasma Theory group and Dana Knoll of the Lab's Fluid Dynamics group presented their findings at the American Geophysical Union meeting in San Francisco at the Moscone Convention Center.

The theory is based on a 19th century mathematical observation called Kelvin-Helmholtz instability. "What we are trying to determine is why magnetic field lines loop out from the surface of the sun, reconnect and then fall back," said Lapenta. "And why these systems, which look very stable, are in fact quite unstable."

According to Lapenta, reconnection rates based on resistivity are orders of magnitude too slow to explain observed coronal reconnections. One possible mechanism that provides fast reconnection rates is known as "driven" reconnection-where external forces drive field lines together in a way that is independent of resistivity. Lapenta and Knoll believe that related work focused on magnetic field line reconnection in Earth's magnetopause has shown that the Kelvin-Helmholtz instability can cause compressive actions that push field lines together and drive reconnection. "We propose that the same mechanism at work in the magnetopause could conceivably be at work in the solar corona and elsewhere," said Lapenta.

In this theory, motion on the visible surface of the sun - the photosphere - leads to twisting deformation waves that move through the chromosphere, a layer of solar atmosphere just above the photosphere, growing larger as they move and emerging with a rapid increase of speed through the sun's corona, or outer atmosphere. This rapid change in speed, or velocity shear, injected into the corona can cause magnetic loops to reconnect, according to Lapenta.

"We have conducted a series of simulations and shown that indeed reconnection can be achieved trough local compression driven by Kelvin- Helmholtz and that the reconnection rate is not sensitive to resistivity," said Lapenta.

From this beginning point, Lapenta hopes to study the processes tied to motion on the surface of the sun to better understand why these "velocity shears" occur and how they move away from the sun and lead to CMEs and other solar events, and to apply this knowledge to better understanding the magnetic fields around the earth and the disc-shaped rotating masses, or accretion discs, that form around some black holes.

###Los Alamos National Laboratory is operated by the University of California for the National Nuclear Security Administration (NNSA) of the U.S. Department of Energy and works in partnership with NNSA's Sandia and Lawrence Livermore national laboratories to support NNSA in its mission.

Los Alamos enhances global security by ensuring the safety and reliability of the U.S. nuclear stockpile, developing technologies to reduce threats from weapons of mass destruction, and solving problems related to energy, environment, infrastructure, health and national security concerns.

Additional news about Los Alamos is available online at http://www.lanl.gov.


Story Source:

The above story is based on materials provided by Los Alamos National Laboratory. Note: Materials may be edited for content and length.


Cite This Page:

Los Alamos National Laboratory. "New Theory Unravels Magnetic Instability." ScienceDaily. ScienceDaily, 11 December 2002. <www.sciencedaily.com/releases/2002/12/021211084037.htm>.
Los Alamos National Laboratory. (2002, December 11). New Theory Unravels Magnetic Instability. ScienceDaily. Retrieved July 30, 2014 from www.sciencedaily.com/releases/2002/12/021211084037.htm
Los Alamos National Laboratory. "New Theory Unravels Magnetic Instability." ScienceDaily. www.sciencedaily.com/releases/2002/12/021211084037.htm (accessed July 30, 2014).

Share This




More Space & Time News

Wednesday, July 30, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Supply Ship Takes Off for International Space Station

Supply Ship Takes Off for International Space Station

AFP (July 30, 2014) The European Space Agency's fifth Automated Transfer Vehicle (ATV-5) is takes off to the International Space Station on an Ariane 5 rocket from French Guiana. Duration: 00:34 Video provided by AFP
Powered by NewsLook.com
Raw: Rocket Launches Into Space With Cargo Ship

Raw: Rocket Launches Into Space With Cargo Ship

AP (July 30, 2014) Arianespace launched a rocket Tuesday from French Guiana carrying a robotic cargo ship to deliver provisions to the International Space Station. (July 30) Video provided by AP
Powered by NewsLook.com
In Virginia, the Rise of a New Space Coast

In Virginia, the Rise of a New Space Coast

AP (July 30, 2014) Every summer, tourists make the pilgrimage to Chincoteague Island, Va. to see wild ponies cross the Assateague Channel. But, it's the rockets sending to supplies to the International Space Station that are making this a year-round destination. (July 30) Video provided by AP
Powered by NewsLook.com
Russia Saves Gecko Sex Satellite, Media Has Some Fun With It

Russia Saves Gecko Sex Satellite, Media Has Some Fun With It

Newsy (July 27, 2014) The satellite is back under ground control after a tense few days, but with a gecko sex experiment on board, the media just couldn't help themselves. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins