HR: 1330h
AN: SP23B-05    [Abstracts]
TI: On the cooling processes of solar flare loops in the gradual decaying phase---Suppression of conduction and heating by plasma wave turbulence
AU: * Jiang, Y
EM: arjiang@stanford.edu
AF: Department of Physics, Stanford University, Varian Physics Room 323 4060 382 Via pueblo Mall, Stanford, CA 94305-4060 United States
AU: Liu, S
EM: liusm@stanford.edu
AF: Department of Physics, Stanford University, Varian Physics Room 323 4060 382 Via pueblo Mall, Stanford, CA 94305-4060 United States
AU: Liu, W
EM: weiliu@quake.Stanford.EDU
AF: Department of Physics, Stanford University, Varian Physics Room 323 4060 382 Via pueblo Mall, Stanford, CA 94305-4060 United States
AU: Petrosian, V
EM: vahe@astronomy.Stanford.EDU
AF: Department of Physics, Stanford University, Varian Physics Room 323 4060 382 Via pueblo Mall, Stanford, CA 94305-4060 United States
AB: High spectral and spatial resolution observations of RHESSI show that emission in the gradual phase of many solar flares is dominated by a thermal looptop source, which cools down faster than expected from the radiative cooling but much slower than that due to the cooling by classical Spitzer conductivity. This could be due to a continuous energy input at a rate equal to the conduction rate. One would then expect a nearly isothermal loop with an almost uniform emission along the loop and significant energy injections at the foot points. However, the looptop image is resolved along the loop and appears to be confined to the top portion of the loop. This requires a suppression of conduction within the source region. Combining imaging spectroscopic observations of RHESSI with the GOES light curves, we model the evolution of the loops in the gradual phase of several flares. We find that the suppression of conduction alone can not account for the RHESSI observations in a quasi-steady equilibrium loop model. A sustained (although declining) energy input is also needed. Thermal damping of turbulence produced continuously (albeit at a declining rate) during the decay phase can be responsible for the heating process. Presence of turbulence could also suppress the conduction rate. This work is supported by NASA grants NAG5-12111, NAG5 11918-1, and NSF grant ATM-0312344.
UR: http://www.stanford.edu/~~arjiang/work.html
DE: 7500 SOLAR PHYSICS, ASTROPHYSICS, AND ASTRONOMY
DE: 7519 Flares
DE: 7554 X rays, gamma rays, and neutrinos
SC: Solar Physics Division - AAS [SP]
MN: 2005 Joint Assembly