Magnetic helicity balance during a filament eruption that occurred in active region NOAA 9682

Zuccarello, F.; Romano, P.; Zuccarello, F.; Poedts, Stefaan

doi:10.1051/0004-6361/201116700

Cited by 13 publications

(13 citation statements)

References 16 publications

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“…Later, the Eastern footpoint also showed the rotational motion and there was a jump in the positive helicity after the initiation of the filament eruption. This can be attributed to the expansion of the filament flux rope and subsequent torque imbalance as has been suggested by Parker (1974); Chae et al (2003) and observed by Smyrli et al (2010); Zuccarello et al (2011). This explains the observations of transient rotational motion in the photospheric footpoints and increased positive magnetic helicity flux after the filament eruption.…”

Section: Summary and Discussionsupporting

confidence: 63%

Filament eruption in association with rotational motion near the filament footpoints

2014

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The active region magnetic field surrounding the filament plays an important role in filament formation, their evolution and disruption. We investigated a filament eruption that occurred in southern hemisphere of the Sun on July 08, 2011 using AIA and HMI data. The filament was located in a region close to the active region NOAA 11247 with its West-most footpoint anchored in the negative polarity plage region and the East-most in the positive polarity plage region. During observations, the magnetic flux was emerging in the active region and also in the plage regions. The flux emergence was stopped in West-most footpoint of the plage region about an hour before the filament eruption. A converging motion was also observed for many hours in the Western footpoint of the filament. The filament had left-handed twist and the net injected magnetic helicity was positive in both footpoints. Both sign of magnetic helicity were observed in the Western footpoint of the filament where the eruption has initiated. Further, an anti-clockwise rotational motion was observed in both the footpoints just after the onset of filament eruption which lasted for 6 min during the eruption process. The emerging flux, converging motion and injection of opposite magnetic helicity could be responsible for destabilizing of the Western footpoint of the filament leading to eruption. The torque imbalance between the expanded portion of the flux tube and the photosphere may have caused the rotation in the footpoint region which changed the trend in the injected magnetic helicity after the filament eruption.

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Section: Summary and Discussionsupporting

confidence: 63%

Filament eruption in association with rotational motion near the filament footpoints

2014

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“…It has been reported that magnetic helicity was impulsively transported across the photosphere in the course of some major flares41112. The authors further noted that the impulsive helicity flux tended to decrease the magnetic helicity of the entire active region.…”

Section: Discussionmentioning

confidence: 93%

“…It is worth noting that the motion of magnetic flux could lead to the transport of magnetic helicity across the photosphere. It has been reported that, in the course of some major flares, magnetic helicity was impulsively transported across the photosphere and that the helicity flux tended to have the sign opposite to that of the active region41112. However, the type of motion pattern responsible for the impulsive helicity transport is still not understood.…”

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confidence: 99%

Observation of a reversal of rotation in a sunspot during a solar flare

Jiang

Yang

et al. 2016

Nat Commun

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The abrupt motion of the photospheric flux during a solar flare is thought to be a back reaction caused by the coronal field reconfiguration. However, the type of motion pattern and the physical mechanism responsible for the back reaction has been uncertain. Here we show that the direction of a sunspot's rotation is reversed during an X1.6 flare using observations from the Helioseismic and Magnetic Imager. A magnetic field extrapolation model shows that the corresponding coronal magnetic field shrinks with increasing magnetic twist density. This suggests that the abrupt reversal of rotation in the sunspot may be driven by a Lorentz torque that is produced by the gradient of twist density from the solar corona to the solar interior. These results support the view that the abrupt reversal in the rotation of the sunspot is a dynamic process responding to shrinkage of the coronal magnetic field during the flare.

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“… 2011 ; Zuccarello et al. 2011 ). This scenario is further supported by MHD simulations by Kusano et al.…”

Section: Long-term and Large-scale Evolution: Observational Aspectsmentioning

confidence: 99%

Flare-productive active regions

Toriumi

Wang

2019

Living Rev Sol Phys

244

151

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Strong solar flares and coronal mass ejections, here defined not only as the bursts of electromagnetic radiation but as the entire process in which magnetic energy is released through magnetic reconnection and plasma instability, emanate from active regions (ARs) in which high magnetic non-potentiality resides in a wide variety of forms. This review focuses on the formation and evolution of flare-productive ARs from both observational and theoretical points of view. Starting from a general introduction of the genesis of ARs and solar flares, we give an overview of the key observational features during the long-term evolution in the pre-flare state, the rapid changes in the magnetic field associated with the flare occurrence, and the physical mechanisms behind these phenomena. Our picture of flare-productive ARs is summarized as follows: subject to the turbulent convection, the rising magnetic flux in the interior deforms into a complex structure and gains high non-potentiality; as the flux appears on the surface, an AR with large free magnetic energy and helicity is built, which is represented by -sunspots, sheared polarity inversion lines, magnetic flux ropes, etc; the flare occurs when sufficient magnetic energy has accumulated, and the drastic coronal evolution affects magnetic fields even in the photosphere. We show that the improvement of observational instruments and modeling capabilities has significantly advanced our understanding in the last decades. Finally, we discuss the outstanding issues and future perspective and further broaden our scope to the possible applications of our knowledge to space-weather forecasting, extreme events in history, and corresponding stellar activities. Electronic supplementary material The online version of this article (10.1007/s41116-019-0019-7) contains supplementary material, which is available to authorized users.

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Magnetic helicity balance during a filament eruption that occurred in active region NOAA 9682

Cited by 13 publications

References 16 publications

Filament eruption in association with rotational motion near the filament footpoints

Filament eruption in association with rotational motion near the filament footpoints

Observation of a reversal of rotation in a sunspot during a solar flare

Flare-productive active regions

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