G. J. J. Botha, T. D. Arber, Abhishek K. Srivastava
It is known from numerical simulations that thermal conduction along magnetic
field lines plays an important role in the evolution of the kink instability in
coronal loops. This study presents the observational signatures of the kink
instability in long coronal loops when parallel thermal conduction is included.
The 3D nonlinear magnetohydrodynamic equations are solved numerically to
simulate the evolution of a coronal loop that is initially in an unstable
equilibrium. The loop has length 80 Mm, width 8 Mm and an initial maximum twist
of Phi = 11.5 pi, where Phi is a function of the radius. The initial loop
parameters are obtained from a highly twisted loop observed in the TRACE 171 A
waveband. Synthetic observables are generated from the data. These observables
include spatial and temporal averaging to account for the resolution and
exposure times of TRACE images. Parallel thermal conduction reduces the maximum
local temperature by up to an order of magnitude. This means that different
spectral lines are formed and different internal loop structures are visible
with or without the inclusion of thermal conduction. However, the response
functions sample a broad range of temperatures. The result is that the
inclusion of parallel thermal conductivity does not have as large an impact on
observational signatures as the order of magnitude reduction in the maximum
temperature would suggest; the net effect is a blurring of internal features of
the loop structure.
View original:
http://arxiv.org/abs/1111.0456
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