Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Scientists unlock the secrets of exploding plasma clouds on the sun

08.11.2010
News from the 52nd annual meeting of the APS Division of Plasma Physics

The Sun sporadically expels trillions of tons of million-degree hydrogen gas in explosions called coronal mass ejections (CMEs). Such clouds—an example is shown in Figure 1a—are enormous in size (spanning millions of miles) and are made up of magnetized plasma gases, so hot that hydrogen atoms are ionized.

CMEs are rapidly accelerated by magnetic forces to speeds of hundreds of kilometers per second to upwards of 2,000 kilometers per second in several tens of minutes. CMEs are closely related to solar flares and, when they impinge on the Earth, can trigger spectacular auroral displays.

They also induce strong electric currents in the Earth's plasma atmosphere (i.e., the magnetosphere and ionosphere), leading to outages in telecommunications and GPS systems and even the collapse of electric power grids if the disturbances are very severe.

Since the first observation of a solar flare in 1859, solar eruptions ("explosions") have attracted much attention from scientists around the world and have been studied with a succession of increasingly sophisticated international satellite missions in the past three decades. A major challenge has been that enormous and complicated plasma structures accelerating away from the Sun can only be observed remotely.

As a result, it has been difficult to test theoretical models to establish a correct understanding of the mechanisms that cause such eruptions. But in 2006, an international twin-satellite mission called STEREO was launched to continuously observe the erupting plasma structures from the Sun to the Earth.

Now, using the data from STEREO, new research by scientists at the Naval Research Laboratory (NRL) in Washington, D.C., demonstrates for the first time that the observed motion of erupting plasma clouds driven by magnetic forces can be correctly explained by a theoretical model. The work will be presented at the 52nd Annual Meeting of the APS Plasma Physics Division.

The theory, controversial when it was first proposed in 1989 by Dr. James Chen of NRL, is based on the concept that an erupting plasma cloud is a giant "magnetic flux rope," a rope of "twisted" magnetic field lines shaped like a partial donut. Chen and Valbona Kunkel, a doctoral student at George Mason University, have applied this model to the new STEREO data of CMEs and shown that the theoretical solutions agree with the measured trajectories of the ejected clouds within the entire field of view from the Sun to the Earth.

The position of the leading edge (LE) of a CME that erupted on December 24, 2007 were tracked by the STEREO-A spacecraft from the earliest stages of eruption to its arrival at 1 AU approximately five days later. The magnetic field and plasma parameters were measured by the STEREO-B spacecraft. The agreement between theory and data is within 1 percent of the measured position of the LE. Chen and Kunkel's results show that the theoretically predicted magnetic field and plasma properties are in excellent agreement with the measurements aboard STEREO-B. This is the first model that can replicate directly observed quantities near the Sun and the Earth as well as the actual trajectories of CMEs. Prior to STEREO, the motion of CMEs in the region corresponding to HI1 and HI2 data was not observed.

Interestingly, the basic forces acting on solar flux ropes are the same as those in laboratory plasma structures such as tokamaks developed to produce controlled fusion energy. The mechanism described by the theory is also potentially applicable to eruptions on other stars.

Saralyn Stewart | EurekAlert!
Further information:
http://www.utexas.edu

More articles from Physics and Astronomy:

nachricht New NASA study improves search for habitable worlds
20.10.2017 | NASA/Goddard Space Flight Center

nachricht Physics boosts artificial intelligence methods
19.10.2017 | California Institute of Technology

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

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

Im Focus: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

Im Focus: Shrinking the proton again!

Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.

It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

Climate Engineering Conference 2017 Opens in Berlin

10.10.2017 | Event News

 
Latest News

Terahertz spectroscopy goes nano

20.10.2017 | Information Technology

Strange but true: Turning a material upside down can sometimes make it softer

20.10.2017 | Materials Sciences

NRL clarifies valley polarization for electronic and optoelectronic technologies

20.10.2017 | Interdisciplinary Research

VideoLinks
B2B-VideoLinks
More VideoLinks >>>