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Abstract We present an investigation of partial filament eruption on 2012 June 17 in the active region NOAA 11504. For the first time, we observed the vertical splitting process during the partial eruption with high-resolution narrowband images at 10830 Å. The active filament was rooted in a smallδ-sunspot of the active region. Particularly, it underwent the partial eruption in three steps, i.e., the precursor, the first eruption, and the second eruption, while the latter two were associated with a C1.0 flare and a C3.9 flare, respectively. During the precursor, slow magnetic reconnection took place between the filament and the adjoining loops that also rooted in theδ-sunspot. The continuous reconnection not only caused the filament to split into three groups of threads vertically but also formed a new filament, which was growing and accompanied brightening took place around the site. Subsequently, the growing filament erupted together with one group splitted threads, resulted in the first eruption. At the beginning of the first eruption, a subsequent magnetic reconnection occurred between the erupting splitted threads and another ambient magnetic loop. After about 3 minutes, the second eruption occurred as a result of the eruption of two larger unstable filaments induced by the magnetic reconnection. The high-resolution observation provides a direct evidence that magnetic reconnection between filament and its ambient magnetic fields could induce the vertical splitting of the filament, resulting in partial eruption.
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This content will become publicly available on February 4, 2026
Solar Flares Triggered by a Filament Peeling Process Revealed by High-resolution GST Hα Observations
Abstract The dynamic structures of solar filaments prior to solar flares provide important physical clues about the onset of solar eruptions. Observations of those structures under subarcsecond resolution with high cadence are rare. We present high-resolution observations covering preeruptive and eruptive phases of two C-class solar flares, C5.1 (SOL2022-11-14T17:29) and C5.1 (SOL2022-11-14T19:29), obtained by the Goode Solar Telescope at Big Bear Solar Observatory. Both flares are ejective, i.e., accompanied by coronal mass ejections (CMEs). High-resolution Hαobservations reveal details of the flares and some striking features, such as a filament peeling process: individual strands of thin flux tubes are separated from the main filament, followed shortly thereafter by a flare. The estimated flux of rising strands is in the order of 1017Mx, versus the 1019Mx of the entire filament. Our new finding may explain why photospheric magnetic fields and overall active region and filament structures as a whole do not have obvious changes after a flare, and why some CMEs have been traced back to the solar active regions with only nonerupting filaments, as the magnetic reconnection may only involve a very small amount of flux in the active region, requiring no significant filament eruptions. We suggest internal reconnection between filament threads, instead of reconnection to external loops, as the process responsible for triggering this peeling of threads that results in the two flares and their subsequent CMEs.
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- PAR ID:
- 10577608
- Publisher / Repository:
- American Astronomical Society
- Date Published:
- Journal Name:
- The Astrophysical Journal Letters
- Volume:
- 980
- Issue:
- 1
- ISSN:
- 2041-8205
- Page Range / eLocation ID:
- L4
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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