3D evolution of a filament disappearance event observed by STEREO |
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Sanjay Gosain Submitted: 2009-10-06 03:04
A filament disappearance event was observed on 22 May 2008 during
our recent campaign JOP 178. The filament, situated in the southern hemisphere,
showed sinistral chirality consistent with the hemispheric rule. The event was
well observed by several observatories in particular by THEMIS. One day before the disappearance, Hα observations showed up and down flows in adjacent
locations along the filament, which suggest plasma motions along twisted flux
rope. THEMIS and GONG observations show shearing photospheric motions
leading to magnetic flux canceling around barbs. STEREO A, B spacecraft with
separation angle 52.4 degrees, showed quite different views of this untwisting
Flux rope in He II 304 Å images. Here, we reconstruct the 3D geometry of the
Filament during its eruption phase using STEREO EUV He II 304 Å images
and find that the filament was highly inclined to the solar normal. The He II
304 Å movies show individual threads, which oscillate and rise to an altitude of
about 120 Mm with apparent velocities of about 100 km s-1, during the rapid
evolution phase. Finally, as the flux rope expands into the corona, the Filament
disappears by becoming optically thin to undetectable levels. No CME was detected by STEREO, only a faint CME was recorded by LASCO at the beginning
of the disappearance phase at 02:00 UT, which could be due to partial filament
eruption. Further, STEREO Fe XII 195 A images showed bright loops beneath
the filament prior to the disappearance phase, suggesting magnetic reconnection
below the flux rope.
Authors: S. Gosain, B. Schmieder, P. Venkatakrishnan, R. Chandra, G. Artzner
Projects: GONG,SoHO-MDI,STEREO,THEMIS/MTR
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Publication Status: Solar Physics (In Press)
Last Modified: 2009-10-06 05:10
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