Energy ribbons cause solar flare

BY KULVINDER SINGH CHADHA

ASTRONOMY NOW

Posted: 20 April, 2009

Tight ribbons of energy on the Sun called sigmoids have been found to cause explosive solar flare events. X-ray telescopes can see these sigmoids in the Sun's corona (it's tenuous outer atmosphere), but models produced by scientists from St Andrews University and the Harvard Smithsonian Center for Astrophysics explain how they form. The results will be presented at the Joint European National Astronomy Meeting at Hertfordshire University (UK) by Professor Alan Hood and Dr Vasilis Archontis, both from St Andrews.

Figure showing the time evolution and eruption of a sigmoid. The first column shows surfaces of electrical current and the second one shows temperature (white hottest, black coolest). These are both simulations form the model. The third column shows Hinode's observations of a sigmoid. Image: ISAS/JAXA/NAOJ/NASA/STFC/ESA/NSC.

Observations by the Hinode spacecraft's X-ray telescope (XRT) showed the formation and eruption of a sigmoid at high resolution. It revealed that sigmoids have a complex structure: two, J-shaped bundles meeting together to form an 'S' shape. An explosive flare event signals the end of a sigmoid's life. However, no one has been able to explain their complex structure and behaviour until now.

The St Andrews team's model treats sigmoids as consisting of numerous thin, twisted ribbons of electrical current. A flare event occurs when these layers interact, throwing magnetic fields and charged particles into space. Archontis says, "Sigmoids work as 'mangers' or 'cocoons' for solar eruptions and there is a high probability they will result in powerful eruptions and other explosive events." He adds that the new model will help scientists understand how this happens.

Hood explains the importance of predicting solar flare events. "Sigmoids are amongst the most interesting features for scientists trying to forecast solar eruptions as these events can disrupt telecommunications, damage satellites and affect the way navigation systems operate."

Our latest 132-page Astronomy Now special edition is an extravaganza of astronomy for the year ahead, with a complete 30-page guide to observing the planets, moon, meteor showers, two solar eclipses, and the deep sky in 2010.
 U.K. STORE
 E.U. STORE
 U.S. & WORLDWIDE STORE

Hubble Reborn
Hubble Reborn takes the reader on a journey through the Universe with spectacular full-colour pictures of galaxies, nebulae, planets and stars as seen through Hubble's eyes, along the way telling the dramatic story of the space telescope, including interviews with key scientists and astronauts.
 U.K. STORE
 E.U. STORE
 U.S. & WORLDWIDE STORE

3D Universe
Witness the most awesome sights of the Universe as they were meant to be seen in this 100-page extravaganza of planets, galaxies and star-scapes, all in 3D!
 U.K. STORE
 E.U. STORE
 U.S. & WORLDWIDE STORE

This special publication features the photography of British astro-imager Nik Szymanek and covers a range of photographic methods from basic to advanced. Beautiful pictures of the night sky can be obtained with a simple camera and tripod before tackling more difficult projects, such as guided astrophotography through the telescope and CCD imaging.
 U.K. STORE
 E.U. STORE
 U.S. & WORLDWIDE STORE

Explore the Universe with these new versions of the award-winning Starry Night Software. Available now from the Astronomy Now Store.
 U.K. STORE
 E.U. STORE
 U.S. & WORLDWIDE STORE

Astronomy Now is pleased to announce the publication of Exploring Mars. The very best images of Mars taken by orbiting spacecraft and NASA's Spirit and Opportunity rovers fill up the 98 glossy pages of this special edition!
 U.K. STORE
 E.U. STORE
 U.S. & WORLDWIDE STORE

This new poster features some of the best pictures from NASA's amazing Mars Exploration Rovers Spirit and Opportunity.
 U.K. STORE
 E.U. STORE
 U.S. & WORLDWIDE STORE