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arXiv · 1105.2839

RHESSI Line and Continuum Observations of Super-hot Flare Plasma

A. Caspi·R. P. Lin
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Abstract

We use RHESSI high-resolution imaging and spectroscopy observations from ~5 to 100 keV to characterize the hot thermal plasma during the 2002 July 23 X4.8 flare. These measurements of the steeply falling thermal X-ray continuum are well fit throughout the flare by two distinct isothermal components: a super-hot (T > 30 MK) component that peaks at ~44 MK and a lower-altitude hot (T < 25 MK) component whose temperature and emission measure closely track those derived from GOES measurements. The two components appear to be spatially distinct, and their evolution suggests that the super-hot plasma originates in the corona, while the GOES plasma results from chromospheric evaporation. Throughout the flare, the measured fluxes and ratio of the Fe and Fe-Ni excitation line complexes at ~6.7 and ~8 keV show a close dependence on the super-hot continuum temperature. During the pre-impulsive phase, when the coronal thermal and non-thermal continua overlap both spectrally and spatially, we use this relationship to obtain limits on the thermal and non-thermal emission.

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A. Caspi, R. P. Lin. 2011-05-13. RHESSI Line and Continuum Observations of Super-hot Flare Plasma. https://doi.org/10.1088/2041-8205%2F725%2F2%2Fl161

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