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| Paper: |
The Build-Up to Eruptive Solar Events Viewed as the Development of Chiral Systems |
| Volume: |
463, 2nd ATST-EAST Workshop in Solar Physics: Magnetic Fields from the Photosphere to the Corona |
| Page: |
157 |
| Authors: |
Martin, S. F.; Panasenco, O.; Berger, M. A.; Engvold, O.; Lin, Y.; Pevtsov, A. A.; Srivastava, N. |
| Abstract: |
When we examine the chirality or observed handedness of the
chromospheric and coronal structures involved in the long-term
build-up to eruptive events, we find that they evolve in very specific
ways to form two and only two sets of large-scale chiral systems.
Each system contains spatially separated components with
both signs of chirality, the upper portion having negative (positive)
chirality and the lower part possessing positive (negative) chirality.
The components within a system are a filament channel (represented
partially by sets of chromospheric fibrils), a filament (if present),
a filament cavity, sometimes a sigmoid, and always an overlying arcade
of coronal loops. When we view these components as parts of
large-scale chiral systems, we more clearly see that it is not the
individual components of chiral systems that erupt but rather it is
the approximate upper parts of an entire evolving chiral system that
erupts. We illustrate the typical pattern of build-up to eruptive
solar events first without and then including the chirality in each
stage of the build-up. We argue that a complete chiral system has one
sign of handedness above the filament spine and the opposite
handedness in the barbs and filament channel below the filament
spine. If the spine has handedness, the observations favor its having
the handedness of the filament cavity and coronal loops above. As the
separate components of a chiral system form, we show that the system
appears to maintain a balance of right-handed and left-handed
features, thus preserving an initial near-zero net helicity. We
further argue that the chiral systems allow us to identify key sites
of energy transformation and stored energy later dissipated in the
form of concurrent CMEs, erupting filaments and solar flares. Each
individual chiral system may produce many successive eruptive events
above a single filament channel. Because major eruptive events
apparently do not occur independent of, or outside of, these unique
chiral systems, we hypothesize that the development of chiral systems:
(1) are fundamental to the occurrence of eruptive solar events and (2)
preserve an approximate balance between positive and negative helicity
(right and left-handed chirality) while preparing to release energy in
the form of CMEs, erupting filaments, and flares. |
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