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| Image Caption: (Left) Rotating disc in solar prominence. (Right) Superheated jet striking a prominence. The jet is emitted to the left of the prominence and travels in an anticlockwise arc, striking the top of the prominence. Credit: NASA/SDO/Li/Smith/Aberystwyth University |
July 5, 2013 | Red Orbit | Lee Rannals
Scientists studying the solar atmosphere have spotted some fascinating moving features in the Sun’s sky.
A team using the Atmospheric Imaging Assembly (AIA) telescope on board the Solar Dynamics Observatory (SDO) satellite has found unusual solar prominences, including: a giant disc that rotates for several hours; feathery streams as long as fifty Earths; a super-heated jet striking the top of a prominence; and twisted ribbons flowing in opposite directions.
Prominences are cold gaseous features on the Sun with temperatures millions of degrees cooler than the surrounding hot solar atmosphere. They can be seen as features extending outwards from the Sun’s surface. Scientists often call prominences filaments when viewed against the solar disc.
Solar prominences help supply most of the material released in coronal mass ejections (CMEs), which are eruptions on the Sun that leads to space weather.
The new observations of a rotating disc caused by turbulence produced at the interface of two gases of enormously different temperatures.
“We think the rotation is produced when hot gases enter a cold medium in an organized fashion. The magnetic field serves as a thermal barrier between the two media. The resulting rotation can last hours,” said Dr. Xing Li of Aberystwyth University.
Li and colleagues observed persistent horizontal motion of feather streamers from a solar prominence over a period of more than 15 hours. They believe the likely cause is a large-scale, slow restructuring of the magnetic field through a process known as magnetic reconnection.
The scientists also observed a jet of superheated gases that were sucked from the coronal cavity surrounding a prominence. They spiraled up a helical path to strike the top of the prominence.
“The feat of the jet hitting the top of the prominence, and the distances involved, is comparable to a ballistic missile hitting a satellite in geostationary orbit!” said Li.
The SDO observations showed counter-streaming flows at under a million miles per hour along a filament channel consisting of many very thin threads.
“These fabulous motions suggest more complex magnetic structures of filaments/prominences than scientists previously thought,” said Li. “These events are beautiful to observe and also set a fascinating challenge to get to the bottom of the physics involved.”
A team of British Geological Survey (BGS) researchers are working on a program to help scientists better understand how space weather caused by activity on the Sun could affect national grids. They are conducting continuous measurements of the background electric field in the UK to help nations be better prepared for interruptions caused by the Sun’s CMEs.
Source: Lee Rannals for redOrbit.com - Your Universe Online
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