RHESSI LINE AND CONTINUUM OBSERVATIONS OF SUPER-HOT FLARE PLASMA
- Space Sciences Laboratory and Department of Physics, University of California, Berkeley, CA 94720-7450 (United States)
We use RHESSI high-resolution imaging and spectroscopy observations from {approx}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{sub e} > 30 MK) component that peaks at {approx}44 MK and a lower-altitude hot (T{sub e} {approx}< 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 {approx}6.7 and {approx}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.
- OSTI ID:
- 21454889
- Journal Information:
- Astrophysical Journal Letters, Vol. 725, Issue 2; Other Information: DOI: 10.1088/2041-8205/725/2/L161; ISSN 2041-8205
- Country of Publication:
- United States
- Language:
- English
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