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The magnetic breakout model explains a variety of solar eruptions, ranging from small-scale jets to large-scale coronal mass ejections (CMEs). Most of our previous studies are focused on jets and CMEs in single null-point topologies. Here, we investigate the initiation of CMEs and associated particle acceleration in a double null-point (or nested fan-spine) topology during multiple homologous M- and X-class flares from an active region. The initiation of the flare and associated eruption begins with inflow structures moving toward the inner null of the closed fan-spine topology. Simultaneous slow flare reconnection below a small filament formed a hot flux rope along with expansion of the overlying flux during slow breakout reconnection at the inner null. The first explosive breakout reconnection of the flux rope at the inner null produced a circular and a remote ribbon along with successful eruption of the flux rope and associated fast EUV (shock) wave. Simultaneous flare reconnection beneath the erupting flux rope produced a typical two-ribbon flare along with two hard X-ray footpoint sources. When the flux rope (with shock) reaches the outer null, a second explosive breakout reconnection produces another large-scale remote ribbon. The radio observations reveal quasiperiodic Type III bursts (period = 100 s) and a Type II burst during the breakout reconnection near the inner and outer nulls, along with gradual solar energetic particles observed at 1 au for magnetically connected events. This study highlight the importance of two successive breakout reconnections in the initiation of CMEs in nested-null topologies and associated particle acceleration and release into the interplanetary medium. The particles are accelerated by the shock ahead of the flux rope, which formed during the inner breakout reconnection. These findings have significant implications for particle acceleration and escape processes in multiscale null-point topologies that produce jets and CMEs.
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Large Magnetic Flux Rope Formation in an X2.1 Flare Observed on 2011 September 6
Abstract Solar active region 11283 produced an X2.1 flare associated with a solar eruption on 2011 September 6. Observations revealed a preflare sigmoidal structure and a circular flare ribbon surrounding the typical two-ribbon structure, along with remote brightenings located at a considerable distance from the main flare site. To interpret these observations in terms of the dynamics of the three-dimensional coronal magnetic field, we conducted data-constrained magnetohydrodynamic simulations. Using a nonlinear force-free field as the initial condition, we reconstructed a realistic preflare magnetic environment, capturing a sheared sigmoid above the polarity inversion line surmounted by a fan–spine structure. Our simulations revealed that reconnection between the sigmoidal field, the adjacent fan–dome field lines, and the neighboring large loops facilitated the transfer of magnetic twist and led to the formation of a large magnetic flux rope (MFR). This transfer and propagation of twist are clearly visible throughout the MFR. As reconnection progresses, the entire fan–spine structure expands along with the evolving MFR. A notable outcome of the simulation is that the footpoints of the newly formed MFR align closely with the observed circular flare ribbon and the remote brightening region. Our findings suggest that a large MFR formed during the X2.1 flare, providing a coherent explanation for the observed phenomena.
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- PAR ID:
- 10676073
- Publisher / Repository:
- IOP Publishing
- Date Published:
- Journal Name:
- The Astrophysical Journal
- Volume:
- 997
- Issue:
- 1
- ISSN:
- 0004-637X
- Page Range / eLocation ID:
- 51
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript
- Journal Article:
- https://doi.org/10.3847/1538-4357/ae2122
