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Yang Liu Submitted: 2008-04-14 11:09
Using a Potential Field Source Surface model (PFSS), we study magnetic field overlying
erupted filaments in solar active regions. The filaments studied here were reported to
experience a kink instability or a torus instability. The torus instability leads to a
full eruption, while the kink instability leads to a full eruption or a failed eruption.
It is found that for full eruption the field decreases with height more quickly than that
for failed eruption. A dividing line between full eruption and failed eruption is also
found to be likely connected with the decay index {it n} of the horizontal potential
field due to sources external of the filament ( (n=-d~log(Bex)/d~log(h) ),
where h is height): the decay index of failed eruption tends to be smaller than that
of full eruption. The difference of the decay indexes between full eruption and failed
eruption is statistically significant. These are supportive of previous theoretical and
numerical simulation results. Another significant difference is the field strength at
low altitude: for failed eruption, the field strength is about a factor of 3 stronger
than that for the full eruption. It suggests that the field strength at low altitude may
be another factor in deciding whether or not a full eruption can take place. On the
other hand, the decay index for the torus-instability full eruption events exhibits
no trend to exceed the decay index for the kink-instability full eruption events on
average, different from a suggestion derived from some MHD simulations. We
discuss possible reasons that may cause this discrepancy.
Authors: Yang Liu
Projects: None
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Publication Status: ApJL, accepted
Last Modified: 2008-09-23 21:10
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