Recurrent CME-like Eruptions in Emerging Flux Regions. I. On the Mechanism of Eruptions

Syntelis, P.; Archontis, V.; Tsinganos, K.

doi:10.3847/1538-4357/aa9612

Cited by 30 publications

(48 citation statements)

References 53 publications

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“…The rotation continues until the bipole is aligned east-west with a Hale orientation. This aspect of rotation has also been seen in flux emergence simulations (Syntelis et al 2017). The region reaches its peak unsigned magnetic flux on 2012 March 17 at 15:58 UT (Figure 1(b)), where the unsigned magnetic flux is defined as half the sum of the total positive and negative flux.…”

Section: Photospheric Magnetic Field Evolutionmentioning

confidence: 62%

Simulating the Coronal Evolution of AR 11437 Using SDO/HMI Magnetograms

Yardley

Mackay

Green

2018

ApJ

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The coronal magnetic field evolution of AR 11437 is simulated by applying the magnetofrictional relaxation technique of Mackay et al. A sequence of photospheric line-of-sight magnetograms produced by the Solar Dynamics Observatory (SDO)/Helioseismic Magnetic Imager (HMI) is used to drive the simulation and continuously evolve the coronal magnetic field of the active region through a series of nonlinear force-free equilibria. The simulation is started during the first stages of the active region emergence so that its full evolution from emergence to decay can be simulated. A comparison of the simulation results with SDO/Atmospheric Imaging Assembly (AIA) observations show that many aspects of the active region's observed coronal evolution are reproduced. In particular, it shows the presence of a flux rope, which forms at the same location as sheared coronal loops in the observations. The observations show that eruptions occurred on 2012 March 17 at 05:09 UT and 10:45 UT and on 2012 March 20 at 14:31 UT. The simulation reproduces the first and third eruption, with the simulated flux rope erupting roughly 1 and 10 hr before the observed ejections, respectively. A parameter study is conducted where the boundary and initial conditions are varied along with the physical effects of Ohmic diffusion, hyperdiffusion, and an additional injection of helicity. When comparing the simulations, the evolution of the magnetic field, free magnetic energy, relative helicity and flux rope eruption timings do not change significantly. This indicates that the key element in reproducing the coronal evolution of AR 11437 is the use of line-of-sight magnetograms to drive the evolution of the coronal magnetic field.

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Section: Photospheric Magnetic Field Evolutionmentioning

confidence: 62%

Simulating the Coronal Evolution of AR 11437 Using SDO/HMI Magnetograms

Yardley

Mackay

Green

2018

ApJ

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“…The reconnection of J-loop field lines form new weakly twisted field lines, forming a sigmoidal twisted MFR (e.g. orange lines, panel d) [58,75]. This is a post-emergence MFR and is not associated with the axis of the sub-photospheric flux tube.…”

Section: Numerical Simulations (A) Atmospheric Mfr Formationmentioning

confidence: 99%

“…Such an example was studied using flux-emergence simulations [58,65]. In Syntelis et al 2017 [58], a field free atmosphere was assumed in order to avoid any external reconnection. During the simulation, a MFR is formed inside the magnetic envelope through shearing and reconnection (e.g.…”

Section: (B) Eruptionsmentioning

confidence: 99%

The emergence of magnetic flux and its role on the onset of solar dynamic events

Archontis

Syntelis

2019

Phil. Trans. R. Soc. A.

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A plethora of solar dynamic events, such as the formation of active regions, the emission of jets and the occurrence of eruptions is often associated with the emergence of magnetic flux from the interior of the Sun to the surface and above. Here, we present a short review on the onset, driving and/or triggering of such events by magnetic flux emergence. We briefly describe some key observational examples, theoretical aspects and numerical simulations, towards revealing the mechanisms that govern solar dynamics and activity related to flux emergence. We show that the combination of important physical processes like shearing and reconnection of magnetic fieldlines in emerging flux regions or at their vicinity can power some of the most dynamic phenomena in the Sun on various temporal and spatial scales. Based on previous and recent observational and numerical studies, we highlight that, in most cases, none of these processes alone can drive and also trigger explosive phenomena releasing considerable amount of energy towards the outer solar atmosphere and space, such as flares, jets and large-scale eruptions (e.g. coronal mass ejections). In addition, one has to take into account the physical properties of the emerging field (e.g. strength, amount of flux, relative orientation to neighbouring and pre-existing magnetic fields, etc.) in order to better understand the exact role of magnetic flux emergence on the onset of solar dynamic events. This article is part of the theme issue ‘Solar eruptions and their space weather impact’.

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“…The field lines of the two magnetic lobes located lower in the atmosphere adopt a J-like shape (pink field lines, 6a, b), due to strong shearing and rotation at their foot-points and due to the emergence of more horizontal field as flux emergence continues (e.g. Syntelis et al 2017). Another current sheet is formed at the interface between the J-like field lines ("lower current sheet", Fig.…”

Section: First Confined Eruptionmentioning

confidence: 99%

“…The flux rope core is associated with cooler temperatures, higher densities and a dominate axial magnetic field component. We therefore identify the flux rope's axis by examining temperature, density and axial magnetic field, across 2D vertical planes, perpendicular to the flux rope (similar to Syntelis et al 2017). The height-time profile of the flux rope is shown in Fig.…”

Section: First Confined Eruptionmentioning

confidence: 99%

Eruptions and flaring activity in emerging quadrupolar regions

Syntelis

Lee

Fairbairn

et al. 2019

A&A

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Context. Solar observations suggest that some of the most dynamic active regions are associated with complex photospheric magnetic configurations such as quadrupolar regions, and especially ones having a δ-spot configuration and a strong Polarity Inversion Line (PIL). Aims. We study the formation and eruption of magnetic flux ropes in quadrupolar regions. Methods. We perform 3D MHD simulations of the partial emergence of a highly twisted flux tube from the solar interior into a non-magnetized stratified atmosphere. We introduce a density deficit at two places along the length of the subphotospheric flux tube to emerge two Ω-shaped loops, forming a quadrupolar region. Results. At the photosphere, the emerging flux forms two initially separated bipoles, that later come in contact creating a δ-spot central region. Above the two bipoles, two magnetic lobes expand and interact through a series of current sheets at the interface between them. Two recurrent confined eruptions are produced. In both cases, reconnection between sheared low-lying field lines forms a flux rope. Reconnection between the two lobes higher in the atmosphere forms field lines that retract down and push against the flux rope, creating a current sheet between them. It also forms field lines that create a third magnetic lobe between the two emerged ones, that later acts as a strapping field. The flux rope eruptions are triggered when the reconnection between the flux ropes and the field above them becomes efficient enough to remove the tension of the overlying field. These reconnection events occur internally in the quadrupolar system, as the atmosphere is non-magnetized. The flux rope of the first, weaker, eruption almost fully reconnects with the overlying field. The flux rope of the second, more energetic, eruption is confined by the overlying strapping field. During the second eruption, the flux rope is enhanced in size, flux and twist, similar to confined-flare-to-flux-rope observations. Proxies of the emission reveal the two erupting filaments channels. A flare arcade is formed only in the second eruption due to the longer lasting and more efficient reconnection at the current sheet below the flux rope.

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Recurrent CME-like Eruptions in Emerging Flux Regions. I. On the Mechanism of Eruptions

Cited by 30 publications

References 53 publications

Simulating the Coronal Evolution of AR 11437 Using SDO/HMI Magnetograms

Simulating the Coronal Evolution of AR 11437 Using SDO/HMI Magnetograms

The emergence of magnetic flux and its role on the onset of solar dynamic events

Eruptions and flaring activity in emerging quadrupolar regions

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