Cloud exploding from Sun ripples like clouds on Earth

Saturday, February 5, 2011

WASHINGTON - Scientists studying new images of clouds of material exploding from the Sun have spotted instabilities forming in that exploding cloud that are similar to those seen in clouds in Earth’s atmosphere.

The study, led by a researcher at the University of Warwick, could greatly assist physicists trying to understand and predict our Solar System’s ‘weather.’

The researchers made their discovery when examining new images of clouds of material exploding from the Sun known as coronal mass ejections (CMEs). These images were provided by the Atmospheric Imaging Assembly (AIA) experiment on NASA’s Solar Dynamics Observatory (SDO).

The new SDO/AIA observations provided images of coronal mass ejections in the extreme ultraviolet at a temperature that was not possible to observe in previous instruments: 11 million Kelvin.

On examining these images the Warwick researchers spotted a familiar pattern of instability on one flank of an exploding cloud of solar material that closely paralleled instabilities seen in Earth’s clouds and waves on the surfaces of seas.

When observed these Kelvin-Helmholtz (or KH) instabilities appear to roll up into growing whirls at boundaries between things moving at different speeds, for instance the transition between air and water or cloud. The difference in speeds produces the boundary instabilities.

Similar conditions can occur when one looks at the magnetic environment of the path of these coronal mass ejections as they travel through the solar corona. The difference in speed and energies between the two creates the very similar KH instabilities that we can observe in clouds.

“The fact that we now know that these KH instabilities in CMEs are so far only observable in the extreme ultraviolet, at a temperature of 11 millionelvin, will also help us in modeling CME behavior,” said University of Warwick researcher Claire Foullon.

“This new observation may give us a novel insight into why these CMEs appear to both rotate, and be deflected away from following a simple straight path from the surface of the Sun. If the instabilities form on just one flank they will may increase drag one side of the CME causing it to move slower than the rest of the CME,” added Foullon. (ANI)

Filed under: Science and Technology

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