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High energy radiation illuminates Sun's magnetic field

The influence of the Sun on the Earth is known as Space Weather and has been identified as a major theme in US space research. Space Weather affects the operation of Earth orbiting satellites, can disturb terrestrial power systems, and provides a hazard for astronauts working in space. Understanding the source regions of solar storms is a crucial component in our attempts to predict Space Weather. Rice Physics and Astronomy graduate student, Aaron Coyner, working under the supervision of Prof. David Alexander, has recently shed some light on how complex magnetic fields in the atmosphere of the Sun release energy to produce fast-moving electrons and drive solar flares. Using a combination of high resolution data from two space-based telescopes, the Transition Region and Coronal Explorer (TRACE) and the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI), Coyner and Alexander have found important differences in the location of the ultraviolet and hard X-ray emission associated with the observed flare. Both sets of emission indicate the interaction of fast moving electrons with the denser parts of the solar atmosphere. What is interesting is that while the UV and X-ray emissions are correlated in time, they are emitted from widely separated (~70,000 km) locations on the Sun. This points to a complex structuring of the unobservable magnetic fields which, not only provide the energy for the particles but define the pathways by which they move through the atmosphere. The Coyner and Alexander results suggest the presence of interacting magnetic structures known as separatrices and provide evidence supporting models for rapid energy release at the intersections of such structures.

Figure shows ultraviolet emission from the TRACE satellite for a flare occurring on July 17, 2002. This emission takes the form of two elongated ribbons. The circle indicates the location of high energy X-ray emission from the RHESSI telescope. The x-ray emission shows a temporal correlation with the northernmost UV ribbon some 70,000 km away.

A copy of the paper can be found at this link

Citation is: Astrophysical Journal, Volume 640, 1 March 2006