Stereoscopic observations of Coronal Hard X-ray flare emissions with Ulysses and RHESSI

Details Stereoscopic observations of Coronal Hard X-ray flare emissions with Ulysses and RHESSI Stereoscopic observations of Coronal Hard X-ray flare emissions with Ulysses and RHESSI

Dec 2005

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2005agufmsh13a0289k&link_type=abstract

American Geophysical Union, Fall Meeting 2005, abstract #SH13A-0289

Statistics

7519 Flares, 7554 X-Rays, Gamma Rays, And Neutrinos

Scientific paper

One of the major findings of the Yohkoh mission is the existence of coronal hard X-ray (HXR) sources above hot flare loops. The emission mechanism that produces these coronal sources is not understood. Coronal HXR sources are rather rarely observed, possible because of limited dynamic range of our observations that makes it difficult to see faint coronal sources next to bright footpoint emissions. For flares occurring just behind the solar limb, the footpoint emission can be occulted and coronal sources can therefore be observed independently. In this work, we were using Ulysses and RHESSI hard X-ray observations that often provides largely different flare view angles to study coronal HXR sources in partly occulted flares. Out of 112 flares seen by Ulysses, we find 5 flares that are partly occulted (5 to 15 degrees) from the RHESSI point of view, but are fully seen (i.e. on disk) by Ulysses. The flare with the best statistics (April 4, 2002, 16UT) reveals the existence of a coronal HXR source that is about 12±2 times fainter than the total HXR emission seen by Ulysses. The coronal source seen with RHESSI shows a relatively steep, progressively hardening power law spectra clearly favoring a non-thermal interpretation. The power law index decreases from ~4.5 at the beginning of the main peak to around 3.0 at the end with a value of ~3.5±0.1 at the peak. Reliable Ulysses spectra can only be derived during the peak of the event showing a power spectra slightly stepper around 3.0±0.2. The relatively small difference in the power law indices clearly excludes a simple explanation of thick target emission in footpoints and thin target emission in the corona. The observed spectral hardening can be partly explained by trapping of electrons in the corona.

Affiliated with

Also associated with

No associations

Rating

Stereoscopic observations of Coronal Hard X-ray flare emissions with Ulysses and RHESSI does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Stereoscopic observations of Coronal Hard X-ray flare emissions with Ulysses and RHESSI, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Stereoscopic observations of Coronal Hard X-ray flare emissions with Ulysses and RHESSI will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-756490