Are complex magnetic field structures responsible for the confined X-class flares in super active region 12192?
arXiv:1707.03171 · doi:10.3847/1538-4357/aa7e7d
Abstract
From 2014 October 19 to 27, six X-class flares occurred in super active region (AR) 12192. They were all confined flares and were not followed by coronal mass ejections (CMEs). To examine the structures of the four flares close to the solar disk center from October 22 to 26, we employ firstly composite triple-time images in each flare process to display {the stratified structure} of these flare loops. The loop structures of each flare in both lower (171 Å) and higher (131 Å) temperature channels are complex, e.g., the flare loops rooting at flare ribbons are sheared or twisted (enwound) together, and the complex structures have not been destroyed during the flares. For the first flare, although the flare loop system appears as a spindle shape, we can estimate their structure from observations, with lengths ranging from 130 to 300 Mm, heights from 65 to 150 Mm, widths at the middle part of the spindle from 40 to 100 Mm, and shear angles from 16 to 90. Moreover, the flare ribbons display irregular movements, such as the left ribbon fragments of the flare on 22 swept a small region repeatedly, and the both ribbons of the flare on 26 moved along the same direction, instead of separating from each other. These irregular movements also imply that the corresponding flare loops are complex, e.g. several sets of flare loops are twisted together. Although previous studies suggest that the background magnetic fields prevent confined flares from erupting, we firstly suggest based on these observations that the complex flare loop structures may be responsible for these confined flares.
16 pages, 5 figures, accepted for publication in ApJ
References in corpus (10)
- Why Is the Great Solar Active Region 12192 Flare-Rich But CME-Poor?
- Slow Rise and Partial Eruption of a Double-Decker Filament. I Observations and Interpretation
- The Confined X-class Flares of Solar Active Region 2192
- Interaction between a fast rotating sunspot and ephemeral regions as the origin of the major solar event on 2006 December 13
- Catastrophe versus instability for the eruption of a toroidal solar magnetic flux rope
- Quasi-periodic Slipping Magnetic Reconnection During an X-class Solar Flare Observed by the Solar Dynamics Observatory and Interface Region Imaging Spectrograph
- Slow Rise and Partial Eruption of a Double-Decker Filament. II. Modeling by a Double Flux Rope Equilibrium
- An Unorthodox X-Class Long-Duration Confined Flare
- Fine Structures and Overlying Loops of Confined Solar Flares
- On the Brightening Propagation of Post-Flare Loops Observed by TRACE