Identification of Pre-flare Processes and Their Possible Role in Driving a Large-scale Flux Rope Eruption with Complex M-class Flare in the Active Region NOAA 12371

Mitra, Prabir K.; Joshi, Bhuwan; Prasad, A.

doi:10.1007/s11207-020-1596-2

Cited by 22 publications

(20 citation statements)

References 73 publications

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“…However, the main energy storage and release of the compound event occurs at the "main" section of the PIL (along the core filament), where the primary ribbon pair, the flare loops, and the nonthermal microwave source form. The total vertical current flowing at the photopspheric level in the area of the third ribbon is more than an order of magnitude weaker than the total current in the area of the primary ribbon pair (Mitra et al 2020). Therefore, we focus on this core region in analyzing and interpreting the event.…”

Section: Observations 21 Flare Light Curves and Ribbonsmentioning

confidence: 91%

“…A third ribbon, marked as R 3 in Figure 2(a), brightens from ≈00:50 UT, simultaneous with the first precursor, and remains visible throughout the event, with variable brightness. Mitra et al (2020) have shown that this ribbon traces a quasi-separatrix layer (QSL) between the flux overlying the core filament and flux that closes locally above weak mixed polarity in the area of the third ribbon, where another filament lies. This filament slowly rises and is activated during the precursors, which initiates the third ribbon, but it does not erupt.…”

Section: Observations 21 Flare Light Curves and Ribbonsmentioning

confidence: 98%

“…This filament slowly rises and is activated during the precursors, which initiates the third ribbon, but it does not erupt. From the timing of the third ribbon, Mitra et al (2020) suggested that the underlying reconnection triggered The northern ribbon extension is also marked. (c-d) AIA 193 Å images showing coronal loops which are nearly cospatial with the southern elbow of the sigmoidal main hot channel when it first lights up and with the initially overlying, moderately sheared flux (orange field lines in Figure 6).…”

Section: Observations 21 Flare Light Curves and Ribbonsmentioning

confidence: 99%

“…The specifics of the eruptive flare were already analyzed in Lee et al (2018). The compound event was recently also analyzed by Mitra et al (2020); we will discuss their partly different conclusions below.…”

Section: Introductionmentioning

confidence: 99%

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Nonequilibrium Flux Rope Formation by Confined Flares Preceding a Solar Coronal Mass Ejection

Kliem

Lee

et al. 2021

ApJ

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We present evidence that a magnetic flux rope was formed before a coronal mass ejection (CME) and its associated long-duration flare during a pair of preceding confined eruptions and associated impulsive flares in a compound event in NOAA Active Region 12371. Extreme-ultraviolet images and the extrapolated nonlinear force-free field show that the first two (impulsive) flares, SOL2015-06-21T01:42, result from the confined eruption of highly sheared low-lying flux, presumably a seed flux rope. The eruption spawns a vertical current sheet, where magnetic reconnection creates flare ribbons and loops, a nonthermal microwave source, and a sigmoidal hot channel that can only be interpreted as a magnetic flux rope. Until the subsequent long-duration flare, SOL2015-06-21T02:36, the sigmoid’s elbows expand, while its center remains stationary, suggesting nonequilibrium but not yet instability. The “flare reconnection” during the confined eruptions acts like “tether-cutting reconnection” whose flux feeding of the rope leads to instability. The subsequent full eruption is seen as an accelerated rise of the entire hot channel, seamlessly evolving into the fast halo CME. Both the confined and ejective eruptions are consistent with the onset of the torus instability in the dipped decay index profile that results from the region’s two-scale magnetic structure. We suggest that the formation or enhancement of a nonequilibrium but stable flux rope by confined eruptions is a generic process occurring prior to many CMEs.

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Section: Observations 21 Flare Light Curves and Ribbonsmentioning

confidence: 91%

Section: Observations 21 Flare Light Curves and Ribbonsmentioning

confidence: 98%

Section: Observations 21 Flare Light Curves and Ribbonsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Nonequilibrium Flux Rope Formation by Confined Flares Preceding a Solar Coronal Mass Ejection

Kliem

Lee

et al. 2021

ApJ

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“…It is well understood that magnetic field remains at the helm of all the catastrophic processes occurring in the solar atmosphere including flares, as the energy released during flares is supplied from the magnetic energy that is stored in the flaring region prior to the flare (see e.g., Shibata & Magara 2011). Therefore, the pre-flare magnetic configuration plays a crucial role in determining the trigger and subsequent evolution of solar flares and associated eruptive phenomena (e.g., Joshi et al 2015Joshi et al , 2017cHernandez-Perez et al 2019;Mitra et al 2020a;Qiu et al 2020).…”

Section: Introductionmentioning

confidence: 99%

Successive occurrences of quasi-circular ribbon flares in a fan-spine-like configuration involving hyperbolic flux tube

Mitra,

Joshi

2021

Preprint

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We present a comprehensive analysis of the formation and evolution of a fan-spine-like configuration that developed over a complex photospheric configuration where dispersed negative polarity regions were surrounded by positive polarity regions. This unique photospheric configuration, analogous to the geological "atoll" shape, hosted four homologous flares within its boundary. Computation of the degree of squashing factor (Q) maps clearly revealed an elongated region of high Q-values between the inner and outer spine-like lines, implying the presence of an hyperbolic flux tube (HFT). The coronal region associated with the photospheric atoll configuration was distinctly identified in the form of a diffused dome-shaped bright structure directly observed in EUV images. A filament channel resided near the boundary of the atoll region. The activation and eruption of flux ropes from the filament channel led to the onset of four eruptive homologous quasi-circular ribbon flares within an interval of ≈11 hours. During the interval of the four flares, we observed continuous decay and cancellation of negative polarity flux within the atoll region. Accordingly, the apparent length of the HFT gradually reduced to a null-point-like configuration before the fourth flare. Prior to each flare, we observed localised brightening beneath the filaments which, together with flux cancellation, provided support for the tether-cutting model of solar eruption. The analysis of magnetic decay index revealed favourable conditions for the eruption, once the pre-activated flux ropes attained the critical heights for torus instability.

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Development of a Confined Circular-Cum-Parallel Ribbon Flare and Associated Pre-Flare Activity

et al. 2020

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Identification of Pre-flare Processes and Their Possible Role in Driving a Large-scale Flux Rope Eruption with Complex M-class Flare in the Active Region NOAA 12371

Cited by 22 publications

References 73 publications

Nonequilibrium Flux Rope Formation by Confined Flares Preceding a Solar Coronal Mass Ejection

Nonequilibrium Flux Rope Formation by Confined Flares Preceding a Solar Coronal Mass Ejection

Successive occurrences of quasi-circular ribbon flares in a fan-spine-like configuration involving hyperbolic flux tube

Development of a Confined Circular-Cum-Parallel Ribbon Flare and Associated Pre-Flare Activity

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