What is the role of the kink instability in solar eruptions? |
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Robert Leamon Submitted: 2002-12-13 13:16
We report the results of two simple studies which seek observational evidence
that solar coronal loops are unstable to the MHD
kink instability above a certain critical value of the total twist.
First, we have used Yohkoh SXT image sequences to measure the shapes
of 191 X-ray sigmoids and to determine the histories of eruption
(evidenced by cusp and arcade signatures) of their associated active regions.
We find that the distribution of sigmoid shapes is quite narrow
and the frequency of eruption does not depend significantly on shape.
Second, we have used Mees Solar Observatory vector magnetograms
to estimate the large-scale total twist of active regions in which
flare-related signatures of eruption are observed.
We find no evidence of eruption for values of large-scale
total twist remotely
approaching the threshold for the kink instability.
Authors: Leamon, R.J., Canfield, R.C., Blehm, Z., and Pevtsov, A.A.
Projects:
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Publication Status: ApJ Letters, 596, L255 (2003)
Last Modified: 2003-11-03 11:00
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