Multi-wavelength observations and modelling of a canonical solar flare |
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Claire Raftery Submitted: 2008-12-01 09:12
This paper investigates the temporal evolution of temperature, emission measure, energy loss and velocity in a C-class solar flare from both an observational and theoretical perspective. The properties of the flare were derived by following the systematic cooling of the plasma through the response functions of a number of instruments - RHESSI (5 MK), GOES-12 (5-30 MK), TRACE 171A (1 MK) and CDS (0.03-8 MK). These measurements were studied in combination with simulations from the 0-D Enthalpy Based Thermal Evolution of Loops (EBTEL) model. At the flare on-set, upflows of ~90 km s-1 and low level emission were observed in Fe XIX, consistent with pre-flare heating and gentle chromospheric evaporation. During the impulsive phase, upflows of ~80 km s-1 in Fe XIX and simultaneous downflows of ~20 km s-1 in He I and O V were observed, indicating explosive chromospheric evaporation. The plasma was subsequently found to reach a peak temperature of ~13 MK in approximately 10 minutes. Using EBTEL, conduction was found to be the dominant loss mechanism during the initial ~300s of the decay phase. It was also found to be responsible for driving gentle chromospheric evaporation during this period. As the temperature fell below ~8 MK, and for the next ~4,000s, radiative losses were determined to dominate over conductive losses. The radiative loss phase was accompanied by significant downflows of <40 km s-1 in O V. This is the first extensive study of the evolution of a canonical solar flare using both spectroscopic and broad-band instruments in conjunction with a hydrodynamic model. While our results are in broad agreement with the standard flare model, the simulations suggest that both conductive and non-thermal beam heating play important roles in heating the flare plasma during the impulsive phase of at least this event.
Authors: Claire L. Raftery, Peter T. Gallagher, Ryan O. Milligan, James A. Klimchuk
Projects: RHESSI,SoHO-CDS,TRACE
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Publication Status: A&A (accepted)
Last Modified: 2008-12-02 09:30
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