Numerical simulation of current sheet formation in a quasiseparatrix layer using adaptive mesh refinement

Effenberger, Frederic; Thust, Kay; Arnold, Lukas; Grauer, Rainer; Dreher, J.

doi:10.1063/1.3565018

Cited by 23 publications

(18 citation statements)

References 14 publications

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“…In contrast, QSLs, quantified by the squashing factor Q ≫1 (Titov et al 2002), are thin volumes where the connectivity of field lines changes drastically but still continuously (Priest & Démoulin 1995;Demoulin et al 1997). Due to the strong distortion of magnetic mapping at QSLs, the generic buildup of intense electric current sheets along QSLs is expected analytically (Demoulin et al 1996), and confirmed later on by numerical simulations (e.g., Aulanier et al 2005;Effenberger et al 2011;Craig & Effenberger 2014). In the case of QSLs, the continuous exchange of connectivity between neighboring field lines induces an apparent "slipping" motion of field lines, which is termed "slipping reconnection" if the speed is sub-Alfvénic, or "slip-running reconnection" if the speed is super-Alfvénic (Aulanier et al 2006).…”

Section: Introductionmentioning

confidence: 80%

Witnessing a Large-scale Slipping Magnetic Reconnection along a Dimming Channel during a Solar Flare

Jing¹,

Li²,

Cheung³

et al. 2017

ApJL

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We report the intriguing large-scale dynamic phenomena associated with the M6.5 flare (SOL2015-06-22T18:23) in NOAA active region 12371, observed by RHESSI, Fermi, and the Atmospheric Image Assembly (AIA) and Magnetic Imager (HMI) on the Solar Dynamic Observatory (SDO). The most interesting feature of this event is a third ribbon (R3) arising in the decay phase, propagating along a dimming channel (seen in EUV passbands) towards a neighboring sunspot. The propagation of R3 occurs in the presence of hard X-ray footpoint emission, and is broadly visible at temperatures from 0.6 MK to over 10 MK through the Differential Emission Measure (DEM) analysis. The coronal loops then undergo an apparent slipping motion following the same path of R3, after a ∼ 80 min delay. To understand the underlying physics, we investigate the magnetic configuration and the thermal structure of the flaring region. Our results are in favor of a slippingtype reconnection followed by the thermodynamic evolution of coronal loops. In comparison with those previously reported slipping reconnection events, this one proceeds across a particularly long distance (∼60 Mm) over a long period of time (∼50 min), and shows two clearly distinguished phases: the propagation of the footpoint brightening driven by nonthermal particle injection and the apparent slippage of loops governed by plasma heating and subsequent cooling.

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Section: Introductionmentioning

confidence: 80%

Witnessing a Large-scale Slipping Magnetic Reconnection along a Dimming Channel during a Solar Flare

Jing¹,

Li²,

Cheung³

et al. 2017

ApJL

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“…While QSLs do not have a discontinuous mapping, the magnetic field line connectivity changes strongly, such that similar current sheets can be expected (Démoulin, Henoux, et al, ). Indeed, current accumulation at QSLs has been demonstrated in MHD simulations (Aulanier et al, ; De Moortel & Galsgaard, ; Effenberger et al, ) and observations (Janvier et al, ).…”

Section: Alfvén Waves and Magnetic Topologymentioning

confidence: 91%

Magnetic Connectivity in the Corona as a Source of Structure in the Solar Wind

et al. 2019

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Five decades of satellite data confirm that the solar wind contains many boundaries separating flow with distinct magnetic and plasma properties. Some speculate the boundaries in the solar wind found at Earth originate at the solar surface and are carried along with the expanding solar wind as fossil structures to 1 AU. This begs the question, is it the physics and magnetic structure above the photosphere that creates well‐defined boundaries between different magnetic flux regions at 1 AU in the solar wind? Magnetic boundaries in the corona exist all the time as topological features of null points in the field. These topological magnetic boundaries seem to be likely locations for plasma boundaries. It can be expected that these boundaries are typical locations where field line‐integrated quantities, such as field‐aligned current, experience large and abrupt changes. We perform three‐dimensional resistive magnetohydrodynamic simulations of the solar corona driven by photospheric foot point motions. We find that large and abrupt changes occur for field line‐integrated quantities across a magnetic topological boundary and the cause for these changes is the discontinuous mapping for magnetic field lines and thus for Alfvén waves across these boundaries. It is also demonstrated via in situ properties that thin layers of field‐aligned and perpendicular currents are frequently located at or close to topological boundaries.

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“…They demonstrate a complex QSL/HFT structure associated with the present magnetic configuration, which has more structures than a "mere" X-shaped crossing. Since the HFT corresponds to the high-Q region, and since intense currents build up where field lines anchored very close to each other have opposite feet widely separated (Démoulin et al 1996a), one can expect the formation of a high-current region around the HFT, such as found in Aulanier et al (2005b) and Effenberger et al (2011) in non-eruptive models. Similar results are obtained here, as shown with the zoom of the current layer on the right panel of Fig.…”

Section: Coronal Magnetic Topology and Electric Currentsmentioning

confidence: 99%

The standard flare model in three dimensions

Janvier

Aulanier

Pariat

et al. 2013

A&A

210

231

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Context. A standard model for eruptive flares aims at describing observational 3D features of the reconnecting coronal magnetic field. Extensions to the 2D model require the physical understanding of 3D reconnection processes at the origin of the magnetic configuration evolution. However, the properties of 3D reconnection without null point and separatrices still need to be analyzed. Aims. We focus on magnetic reconnection associated with the growth and evolution of a flux rope and associated flare loops during an eruptive flare. We aim at understanding the intrinsic characteristics of 3D reconnection in the presence of quasi-separatrix layers (QSLs), how QSL properties are related to the slip-running reconnection mode in general, and how this applies to eruptive flares in particular. Methods. We studied the slip-running reconnection of field lines in a magnetohydrodynamic simulation of an eruptive flare associated with a torus-unstable flux rope. The squashing degree and the mapping norm are two parameters related to the QSLs. We computed them to investigate their relation with the slip-running reconnection speed of selected field lines. Results. Field lines associated with the flux rope and the flare loops undergo a continuous series of magnetic reconnection, which results in their super-Alfvénic slipping motion. The time profile of their slippage speed and the space distribution of the mapping norm are shown to be strongly correlated. We find that the motion speed is proportional to the mapping norm. Moreover, this slip-running motion becomes faster as the flux rope expands, since the 3D current layer evolves toward a current sheet, and QSLs to separatrices.Conclusions. The present analysis extends our understanding of the 3D slip-running reconnection regime. We identified a controlling parameter of the apparent velocity of field lines while they slip-reconnect, enabling the interpretation of the evolution of post flare loops. This work completes the standard model for flares and eruptions by giving its 3D properties.

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Numerical simulation of current sheet formation in a quasiseparatrix layer using adaptive mesh refinement

Cited by 23 publications

References 14 publications

Witnessing a Large-scale Slipping Magnetic Reconnection along a Dimming Channel during a Solar Flare

Witnessing a Large-scale Slipping Magnetic Reconnection along a Dimming Channel during a Solar Flare

Magnetic Connectivity in the Corona as a Source of Structure in the Solar Wind

The standard flare model in three dimensions

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