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Scientists Study Magnetic Reconnection Effects On Space Weather

July 16, 2013
Image Caption: An overlap of data from two NASA spacecraft confirm a sighting of magnetic reconnection on the sun, a process of realigning magnetic fields that lies at the heart of space weather. The teal image, from SDO, shows the shape of magnetic field lines in the sun’s atmosphere. The RHESSI data is in orange. Credit: NASA / SDO / RHESSI / Goddard

Brett Smith for redOrbit.com – Your Universe Online

Using observations from two different NASA spacecraft, scientists have shed new light on the process behind solar flares and eruptions: magnetic reconnection.

Magnetic reconnection occurs when magnetic lines collide and break apart – snapping into new positions and releasing energy in the process. On the sun, magnetic reconnections can result in radiation and solar material being flung across the solar system. These reconnections also take place in Earth’s magnetosphere – albeit with less violent results.

[ Watch the Video: X Marks the Spot: SDO Sees Reconnection ]

The process behind solar magnetic reconnections has so far eluded scientists, partly because the events are difficult to observe as magnetic field lines are invisible.

“The community is still trying to understand how magnetic reconnection causes flares,” said Yang Su, a co-author of the new study and solar scientist at the University of Graz in Austria. “We have so many pieces of evidence, but the picture is not yet complete.”

While searching through imagery from NASA’s Solar Dynamics Observatory (SDO), Su saw direct evidence of magnetic reconnection as it was happening, according to the report in Nature Physics.

The scientists were able to track direct evidence of the magnetic lines’ activity via the charged plasma particles that react to their presence. Orbiting solar telescopes occasionally spot bright lines of plasma looping and arcing through the sun’s atmosphere.

In the SDO images, Su saw two collections of field lines move toward each other, collide and then one set of lines flew into space while the other set fell back onto the Sun.

“It can often be hard to tell what’s truly happening in three dimensions from these images, since the pictures themselves are two-dimensional,” said co-author Gordon Holman, a solar scientist at NASA’s Goddard Space Flight Center in Greenbelt, Md. “But if you look long enough and compare data from other instruments, you can make a good case for what’s going on.”

In order to confirm their initial observations, the team referred to observations of the same event from NASA’s Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI). The imager showed pockets of solar material forming above and below the collision point, a telltale sign of magnetic reconnection. By combining the two sets of data, the scientists’ findings supported previous models and theories.

“This is the first time we’ve seen the entire, detailed structure of this process, because of the high quality data from SDO,” Su said. “It supports the whole picture of reconnection, with visual evidence.”

Su added that the findings could allow for calculations on how quickly the process took and how much material is involved. These calculations could then be used to refine existing models.

Because directly observing magnetic reconnections is extremely difficult, re-creating and studying them in a lab isn’t an option. Solar scientists are expected to investigate the magnetic phenomenon in greater detail with the launch of NASA’s Magnetospheric Multiscale (MMS) mission in 2014. MMS is comprised of four spacecraft that are designed to pass through less violent magnetic reconnection events that take place in Earth’s magnetosphere. Solar scientists say they expect the NASA assets to help them better understand space weather that can disrupt communications on Earth.


Source: Brett Smith for redOrbit.com – Your Universe Online



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