Formation and Reconnection of Three-dimensional Current Sheets with a Guide Field in the Solar Corona

Edmondson, J. K.; Lynch, B. J.

doi:10.3847/1538-4357/aa83ba

Cited by 24 publications

(22 citation statements)

References 102 publications

(128 reference statements)

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“…Our prior analysis of 27 jets in an equatorial coronal hole found no direct correlation between emerging flux and the observed activity: the bright point sources emerged hours to days before any jets were generated (Kumar et al 2019). Our present observations reveal that plasmoids form in the 3D BCS, which is consistent with recent high-resolution 3D MHD simulations of breakout reconnection (Edmondson et al 2010;Wyper & Pontin 2014a,b;Edmondson & Lynch 2017). Our new observations imply that, in fact, plasmoids are a central feature of all fast reconnection.…”

Section: Discussionsupporting

confidence: 92%

First Detection of Plasmoids from Breakout Reconnection on the Sun

Kumar

Karpen

Antiochos

et al. 2019

ApJ

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Transient collimated plasma ejections (jets) occur frequently throughout the solar corona, in active regions, quiet Sun, and coronal holes. Although magnetic reconnection is generally agreed to be the mechanism of energy release in jets, the factors that dictate the location and rate of reconnection remain unclear. Our previous studies demonstrated that the magnetic breakout model explains the triggering and evolution of most jets over a wide range of scales, through detailed comparisons between our numerical simulations and high-resolution observations. An alternative explanation, the resistive-kink model, invokes breakout reconnection without forming and explosively expelling a flux rope. Here we report direct observations of breakout reconnection and plasmoid formation during two jets in the fan-spine topology of an embedded bipole. For the first time, we observed the formation and evolution of multiple small plasmoids with bidirectional flows associated with fast reconnection in 3D breakout current sheets in the solar corona. The first narrow jet was launched by reconnection at the breakout current sheet originating at the deformed 3D null, without significant flare reconnection or a filament eruption. In contrast, the second jet and release of cool filament plasma were triggered by explosive breakout reconnection when the leading edge of the rising flux rope formed by flare reconnection beneath the filament encountered the preexisting breakout current sheet. These observations solidly support both reconnection-driven jet models: the resistive kink for the first jet, and the breakout model for the second explosive jet with a filament eruption.

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Section: Discussionsupporting

confidence: 92%

First Detection of Plasmoids from Breakout Reconnection on the Sun

Kumar

Karpen

Antiochos

et al. 2019

ApJ

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“…The guide field has recently been shown to control both the efficiency of particle acceleration by the Fermi mechanism in plasmoids (Dahlin et al 2016;Arnold et al 2021) and the internal structure of the plasmoids themselves. For example, Edmondson & Lynch (2017) found that the correlation length of magnetic fluctuations along the guide-field direction increases with the guide-field ratio.…”

Section: Theoretical Backgroundmentioning

confidence: 99%

Variability of the Reconnection Guide Field in Solar Flares

Dahlin,

Antiochos,

Qiu

et al. 2021

Preprint

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Solar flares may be the best-known examples of the explosive conversion of magnetic energy into bulk motion, plasma heating, and particle acceleration via magnetic reconnection. The energy source for all flares is the highly sheared magnetic field of a filament channel above a polarity inversion line (PIL). During the flare, this shear field becomes the so-called reconnection guide field (i.e., the non-reconnecting component), which has been shown to play a major role in determining key properties of the reconnection including the efficiency of particle acceleration. We present new high-resolution, three-dimensional, magnetohydrodynamics simulations that reveal the detailed evolution of the magnetic shear/guide field throughout an eruptive flare. The magnetic shear evolves in three distinct phases: shear first builds up in a narrow region about the PIL, then expands outward to form a thin vertical current sheet, and finally is transferred by flare reconnection into an arcade of sheared flare loops and an erupting flux rope. We demonstrate how the guide field may be inferred from observations of the sheared flare loops. Our results indicate that initially the guide field is larger by about a factor of 5 than the reconnecting component, but it weakens by more than an order of magnitude over the course of the flare. Instantaneously, the guide field also varies spatially over a similar range along the three-dimensional current sheet. We discuss the implications of our results for understanding observations of flare particle acceleration.

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“…The formation and instability of current sheets with stretched magnetic field lines is a common problem in both magnetotail and solar physics (Reeves et al., 2008; Terasawa et al., 2000). In the latter case magnetic reconnection is believed to explain charged particle acceleration and magnetic field energy release in eruptive flares (the so called standard CSHKP model, see Carmichael, 1964; Hirayama, 1974; Kopp & Pneuman, 1976; Sturrock, 1966), non‐eruptive events (including, e.g., coalescence of magnetic loops, see Sakai & de Jager, 1996), streamers (e.g., Edmondson & Lynch, 2017; Riley & Luhmann, 2012; Réville et al., 2020), and solar wind current sheets (Gosling, 2012; Phan et al., 2006). In contrast to the magnetotail investigations, mostly focused on the stabilization of the tearing mode by

B_{z}

field, the theory of tearing instability for solar applications is dominated by models of resistive tearing mode in

B_{z} = 0

sheets (e.g., Del Sarto et al., 2016; Dobrowolny et al., 1983; Loureiro et al., 2012; Ofman et al., 1991; Tenerani et al., 2015).…”

Section: Introductionmentioning

confidence: 99%

Stability of the Magnetotail Current Sheet With Normal Magnetic Field and Field‐Aligned Plasma Flows

et al. 2021

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One of the most important problems of magnetotail dynamics is the substorm onset and the related instability of the magneotail current sheet. Since the simplest 2D current sheet configuration with monotonic Bz was proven to be stable to the tearing mode, the focus of the instability investigation moved to more specific configurations, for example, kinetic current sheets with strong transient ion currents and current sheets with non‐monotonic Bz (local Bz minima or/and peaks). The stability of the latter current sheet configuration has been studied both within kinetic and fluid approaches, whereas the investigation of the transient ion effects was limited to kinetic models only. This paper aims to provide a detailed analysis of the stability of a multi‐fluid current sheet configuration that mimics current sheets with transient ions. Using the system with two field‐aligned ion flows that mimic the effect of pressure non‐gyrotropy, we construct a 1D current sheet with a finite Bz. This model describes well recent findings of very thin intense magnetotail current sheets. The stability analysis of this two‐ion model confirms the stabilizing effect of finite Bz and shows that the most stable current sheet is the one with exactly counter‐streaming ion flows and zero net flow. Such field‐aligned flows may substitute the contribution of the pressure tensor nongyrotropy to the stress balance but cannot overtake the stabilizing effect of Bz. Obtained results are discussed in the context of magnetotail dynamical models and spacecraft observations.

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Formation and Reconnection of Three-dimensional Current Sheets with a Guide Field in the Solar Corona

Cited by 24 publications

References 102 publications

First Detection of Plasmoids from Breakout Reconnection on the Sun

First Detection of Plasmoids from Breakout Reconnection on the Sun

Variability of the Reconnection Guide Field in Solar Flares

Stability of the Magnetotail Current Sheet With Normal Magnetic Field and Field‐Aligned Plasma Flows

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