34th Solar Physics Division Meeting, June 2003
Session 22 RHESSI Results III
Oral, Thursday, June 19, 2003, 9:00-10:30am, Auditorium

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[22.06] RHESSI Observations of Coronal Hard X-Ray Sources in Behind-the-limb Solar Flares

S. R. Kane (University of California, Berkeley)

Since the launch of the RHESSI satellite in February 2002, the X-ray/gamma-ray imager on RHESSI has imaged coronal hard X-ray sources associated with about 50 solar flares. The magnitude of the associated soft X-ray flares observed by GOES varied from class C to X. All the flares were apparently located behind the solar limb. The relevant hard X-ray sources were located in the solar corona at heights varying from 5000 km to 50000 km above the photosphere. They occurred during both the impulsive and gradual phases of a flare. The photon spectrum of the “impulsive” sources was, in general, harder than that for the “gradual” sources. In some flares the location of the “gradual” source was found to vary with time, especially during the decay of the flare. In such cases the height of the source generally increased with time. Although the existence of flare-associated hard X-ray sources in the high corona was known before from multi-spacecraft observations, the imager on RHESSI has provided images and spectra which can be used to deduce quantitative characteristics of the hard X-ray source and the energetic electrons responsible for the hard X-ray emission from these sources. Highlights of the RHESSI observations will be presented and their implications regarding the existing models of solar flares will be discussed.


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