34th Solar Physics Division Meeting, June 2003
Session 18 RHESSI Results II
Poster, Wednesday, June 18, 2003, 3:30-5:00pm, Mezzanine

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[18.01] Temporal Variability of Gamma-Ray Lines from the X-Class Solar Flare of 2002 July 23

A. Y. Shih, D. M. Smith, R. P. Lin, S. Krucker (Department of Physics and Space Sciences Laboratory, UC, Berkeley), R. A. Schwartz (NASA GSFC), G. H. Share, R. J. Murphy (E. O. Hulburt Center for Space Research, NRL)

On 2002 July 23, the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) detected a GOES X4.8 solar flare, and analysis of the data has produced the first spectrally resolved measurement of nuclear de-excitation lines in a solar flare. We investigate the temporal variability of the flux of these lines by analyzing the observed spectrum for distinct time intervals of the flare. After the first major burst of the flare, the gamma-ray lines produced by iron, carbon, and oxygen show statistically significant changes in their fluxes relative to the neon line, suggesting that the circumstances of ion acceleration change as the flare progresses. We consider possible causes such as a varying alpha/proton ratio or a varying energy spectrum for the ions. Finally, we correlate these variations with other observed variations of the flare.

The work at the University of California, Berkeley, was supported by NASA contract NAS 5-98033.

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Bulletin of the American Astronomical Society, 35 #3
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