AAS 204th Meeting, June 2004
Session 87 Flares
SPD Oral, Thursday, June 3, 2004, 10:30-11:30am, 704/706

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[87.02] Solar Flare Modeling and RHESSI Data Analysis

L. Sui (Catholic U./GSFC)

I report the results of studies of four solar flares observed with the Ramaty High Energy Solar Spectroscopic Imager (RHESSI). (1) Based on an analysis of a simple limb flare on 2002 Feb. 20, I establish a steady-state loop model in which high-energy electrons are continuously injected at the top of a semicircular loop. The model predications were found to be consistent with the RHESSI results in many respects, but the looptop spectrum from the model is softer than that from the flare images, suggesting the presence of particle acceleration in the loop itself. (2) Three homologous X-ray flares which occurred between April 14 and 16, 2002 were studied. For the April 15 flare, I found that the temperature of the flare loops increased towards higher altitudes, while the temperature of a separate coronal source above the loops increased towards lower altitudes, providing strong evidence for the presence of a current sheet. I also found that an electron low-energy cutoff of 30 keV is required to fit the flare spectra. Furthermore, I found a stationary coronal source above the flare loops and the downward motion of the looptop in the early impulsive phase of all three flares. These new features are believed to be associated with the formation and development of a current sheet in the corona.

This work was supported by RHESSI PI funding.

The author(s) of this abstract have provided an email address for comments about the abstract: lhsui@stars.gsfc.nasa.gov

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