Successive Homologous Coronal Mass Ejections Driven by Shearing and Converging Motions in Solar Active Region NOAA 12371

Vemareddy, P.

doi:10.3847/1538-4357/aa7ff4

Cited by 35 publications

(40 citation statements)

References 96 publications

(139 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The sheared arcade loops are formed through the helicity injection derived from the long term evolution for a few days prior to the flare (Vemareddy 2017). Because the sheared arcade loops are quite stable, some triggering processes are required to make them unstable.…”

Section: Discussionmentioning

confidence: 99%

“…Therefore, the small island might play a key role in accelerating the magnetic reconnection, especially the tether-cutting reconnection. Vemareddy (2017) also suggested that the erupting flux rope should be formed by the tether-cutting reconnection. Figure 6 shows the temporal evolution of the small island.…”

Section: Discussionmentioning

confidence: 99%

“…The AR 12371 is one of very eruptive ARs and produces major M-class flares accompanied with CMEs. During its disk passage, Vemareddy (2017) investigated that sigmoidal structures are formed before the major flares and shearless arcades are reformed after the major flares repeatably by tether-cutting reconnection. In this study, we focus on an eruptive event, the M6.5 flare, in 2015 June 22 when the AR 12371 is located near disk center.…”

Section: Observations and Numerical Methodsmentioning

confidence: 99%

See 2 more Smart Citations

Onset Mechanism of M6.5 Solar Flare Observed in Active Region 12371

Junsang¹,

Inoue²,

Kusano³

et al. 2019

ApJ

View full text Add to dashboard Cite

We studied a flare onset process in terms of stability of a three-dimensional (3D) magnetic field in active region 12371 producing an eruptive M6.5 flare in 2015 June 22. In order to reveal the 3D magnetic structure, we first extrapolated the 3D coronal magnetic fields based on time series of the photospheric vector magnetic fields under a nonlinear force-free field (NLFFF) approximation. The NLFFFs nicely reproduced the observed sigmoidal structure which is widely considered as preeruptive magnetic configuration. We, in particular, found that the sigmoid is composed of two branches of sheared arcade loops. On the basis of the NLFFFs, we investigated the sheared arcade loops to explore the onset process of the eruptive flare using three representative MHD instabilities: the kink, torus and double arc instabilities. The double arc instability, recently proposed by Ishiguro & Kusano, is a double arc loop can be more easily destabilized than a torus loop. Consequently, the NLFFFs are found to be quite stable against the kink and torus instabilities. However, the sheared arcade loops formed prior to the flare possibly becomes unstable against the double arc instability. As a possible scenario on the onset process of the M6.5 flare, we suggest three-step process: (1) double arc loop are formed by the sheared arcade loops through the tether-cutting reconnection during an early phase of the flare, (2) the double arc instability contributes to the expansion of destabilized double arc loops and (3) finally, the torus instability makes the full eruption.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Observations and Numerical Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Onset Mechanism of M6.5 Solar Flare Observed in Active Region 12371

Junsang¹,

Inoue²,

Kusano³

et al. 2019

ApJ

View full text Add to dashboard Cite

show abstract

“…The presence of such hot channel as well as filament are often deemed to be manifestation of a corresponding MFR Zhang et al 2012). More details of observation for this flare and eruption can be found in Vemareddy (2017) and Vemareddy & Demóulin (2018). Figure 2 compares a sequence of the photospheric magnetic configurations around the flare source region with the corresponding EUV observations.…”

Section: Basic Configuration Of the Pre-flare Coronamentioning

confidence: 98%

“…As shown in the second and third column of Figure 3, overall the MFR continues to expand upward and extend its legs to two polarities far apart (N1 and P1 labelled in Figure 2). During the formation process of the MFR, there is hardly any emerging flux in this region observed from the magnetogram, and actually the total unsigned flux decreases in the duration (e.g., see Vemareddy 2017). So the long curved MFR can only be built up in the corona driven by the bottom surface motion rather than direct emergence.…”

Section: Formation Of a Long Flux Ropementioning

confidence: 99%

Data-driven MHD Simulation of the Formation and Initiation of a Large-scale Preflare Magnetic Flux Rope in AR 12371

Jiang

Ping-hua

et al. 2020

ApJ

View full text Add to dashboard Cite

Solar eruptions are the most powerful drivers of space weather. To understand their cause and nature, it is crucial to know how the coronal magnetic field evolves before eruption. Here we study the formation process of a relatively large-scale magnetic flux rope (MFR) in active region NOAA 12371 that erupts with a major flare and coronal mass ejection on 2015 June 21. A data-driven numerical magnetohydrodynamic model is employed to simulate three-dimensional coronal magnetic field evolution of one-day duration before the eruption. Comparison between the observed features and our modeled magnetic field discloses how the pre-eruption MFR forms. Initially, the magnetic field lines were weakly twisted as being simple sheared arcades. Then a long MFR was formed along the polarity inversion line due to the complex photospheric motion, which is mainly shearing rather than twisting. The presence of the MFR is evidenced by a coherent set of magnetic field lines with twist number above unity. Below the MFR a current sheet is shown in the model, suggesting that tether-cutting reconnection plays a key role in the MFR formation. The MFR's flux grows as more and more field lines are twisted due to continuous injection of magnetic helicity by the photospheric motions. Meanwhile, the height of the MFR's axis increases monotonely from its formation. By an analysis of the decay index of its overlying field, we suggest that it is because the MFR runs into the torus instability regime and becomes unstable that finally triggers the eruption.

show abstract