Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Magnetic ’slinky effect’ may power aurora

17.01.2003


The spectacular aurora borealis displays that light up the northern nights could be powered by a gigantic "slinky" effect in Earth’s magnetic field lines, according to research performed at the University of Minnesota. Earth’s magnetic field resemble a slinky in that when "wiggled," it undulates in waves that travel down the field lines at speeds up to 25 million miles per hour. These waves can pass energy to electrons, accelerating them along the magnetic field lines toward Earth. When the electrons hit atoms in the atmosphere, the atoms become excited and produce the colors of the aurora. Using electric and magnetic field data and images from NASA’s POLAR satellite, the researchers showed that energy from such waves is sufficient to power auroras and that statistically, the waves occur in the same locations as auroras--in a ring around the poles. The work will be published in the Jan. 17 issue of Science.




"We don’t know exactly what wiggles the field lines, but similar processes could explain the heating of the solar corona [the sun’s atmosphere], the release of energy during solar flares and the acceleration of the solar wind [a stream of charged particles from the sun]," said physics associate professor John Wygant, second author of the study. "At the edges of sunspots, other researchers have actually seen magnetic field lines waving. Understanding how such waves are caused and how they transmit energy is important to unraveling the complex processes behind larger-scale particle accelerations that occur, for example, in jets of material being ejected from black holes at the centers of galaxies." The paper’s first author is Andreas Keiling, who headed the study while a doctoral student and, later, a research scientist at the University of Minnesota. He is now at the Center for Space Research on Radiation in Toulouse, France.

The ultimate source of energy for auroras is the solar wind. Flowing with the wind--which is mostly single protons and electrons--is a magnetic field that encounters Earth’s own field tens of thousands of miles above the planet surface. Earth is like a huge bar magnet, with magnetic field lines coming out near the poles, curving through space, and re-entering near the opposite pole. When the solar wind’s magnetic field sweeps by, it joins with some of Earth’s magnetic field lines and stretches them into space on the night side of Earth. The stretching energizes this part of the magnetic field until it suddenly "snaps" away from the solar wind and reconnects with Earth. This process, called reconnection, may send waves rippling through the magnetic field, like wiggling a slinky, said Wygant.


Energy from the waves then passes to electrons, sending them in beams along the magnetic field lines into the atmosphere. The color of the aurora depends on how deeply the electrons penetrate the atmosphere and which atoms they excite. Measurements of electrical energy at altitudes near 12,000 miles, where the electrons are accelerated, showed sufficient energy from the waves to power auroras, Wygant said.

Auroras also occur in south polar regions, where they are known as the aurora australis. Waves in the magnetic field lines are called Alfven waves, after Hannes Alfven, a Swedish physicist who helped found the field of plasma physics, said Wygant.

POLAR’s electric field measurements were performed by an instrument built by the University of California at Berkeley. Other authors of the paper are Cynthia Cattell, physics professor, University of Minnesota; Forrest Mozer, professor of physics, Berkeley; and Christopher Russell, professor of physics, UCLA. The work was supported by NASA.



POLAR satellite images of the auroral ring are at www1.umn.edu/urelate/newsservice/aurora.html.

Contacts:
John Wygant, (510) 642-7297 (Jan. 13 and 14), (612) 626-8921 (Jan. 15 and later)
Cynthia Cattell, (612) 626-8918 (until noon Jan. 15)
Andreas Keiling, 33 (0) 561 55 66 60 (Toulouse, France)
Deane Morrison, University News Service, (612) 624-2346


Deane Morrison | EurekAlert!
Further information:
http://www.umn.edu/
http://www1.umn.edu/urelate/newsservice/aurora.html

More articles from Earth Sciences:

nachricht GPM sees deadly tornadic storms moving through US Southeast
01.12.2016 | NASA/Goddard Space Flight Center

nachricht Cyclic change within magma reservoirs significantly affects the explosivity of volcanic eruptions
30.11.2016 | Johannes Gutenberg-Universität Mainz

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

Im Focus: Molecules change shape when wet

Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water

In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...

Im Focus: Fraunhofer ISE Develops Highly Compact, High Frequency DC/DC Converter for Aviation

The efficiency of power electronic systems is not solely dependent on electrical efficiency but also on weight, for example, in mobile systems. When the weight of relevant components and devices in airplanes, for instance, is reduced, fuel savings can be achieved and correspondingly greenhouse gas emissions decreased. New materials and components based on gallium nitride (GaN) can help to reduce weight and increase the efficiency. With these new materials, power electronic switches can be operated at higher switching frequency, resulting in higher power density and lower material costs.

Researchers at the Fraunhofer Institute for Solar Energy Systems ISE together with partners have investigated how these materials can be used to make power...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

UTSA study describes new minimally invasive device to treat cancer and other illnesses

02.12.2016 | Medical Engineering

Plasma-zapping process could yield trans fat-free soybean oil product

02.12.2016 | Agricultural and Forestry Science

What do Netflix, Google and planetary systems have in common?

02.12.2016 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>