A theory of magnetic flux transfer at the Earth's magnetopause

Lee, L. C.; Fu, Zhengyi

doi:10.1029/gl012i002p00105

Cited by 478 publications

(402 citation statements)

References 27 publications

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“…On the other hand, the CS may be thought as an ensemble of mini-structures, not detectable by present instrumentation, where the resistivity problem is alleviated. The filamentary nature of CSs has been predicted theoretically by Lee & Fu (1985) and Lee (1995) and confirmed by CLUSTER observations in the magnetotail (e.g., Slavin et al 2003Slavin et al , 2005Eastwood et al 2005): plasmoids observed by CLUSTER well fit a scenario of multiple X-lines where reconnection takes place and produces plasmoids. Observations have also shown that one of the many X-lines, for so far unknown reasons, becomes dominant (Sharma et al 2008).…”

Section: Cs Inhomogeneitiessupporting

confidence: 54%

Uv Transient Brightenings Associated With a Coronal Mass Ejection

Schettino¹,

Poletto²,

Romoli³

2009

ApJ

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In this paper, we analyze transient UV brightenings in spectra acquired by SOHO/UltraViolet Coronagraph Spectrometer (UVCS) on 2003 June 2 in association with a coronal mass ejection (CME) that occurred at the West limb of the Sun at 08:54 UT. Brightenings have been observed in lines from cool (C iii, O vi), intermediate (Si viii, Si xii), and high ([Fe xviii]) temperature ions over about 7 hr from the CME. Brightenings in cool lines are interpreted in terms of mini-ejections that appear at the time of, and after, the passage of the CME front through the UVCS slit. We give here their temperature and density and we point out that, assuming a spherical shape, a few of these mini-CMEs can provide a mass comparable to that quoted for typical CMEs. Hot lines, like the [Fe xviii] line at 974.9 Å which shows up in the CME associated current sheet (CS), undergo transient brightness as well, but hot lines brightenings are more difficult to interpret. We propose here a scenario where they are signatures of the passage through the UVCS slit of plasmoids similar to those observed in the filamentary CS of the magnetotail that form as a consequence of the tearing-mode instability or of a time-dependent Petschek-type reconnection.

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Section: Cs Inhomogeneitiessupporting

confidence: 54%

Uv Transient Brightenings Associated With a Coronal Mass Ejection

Schettino¹,

Poletto²,

Romoli³

2009

ApJ

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“…However, their formation mechanism and precise signatures remain under debate. Of the leading ideas [29][30][31] , these simulations are more consistent with the multiple-X-line model 30 rather than the single-X-line model 31 , but with important differences. Observationally, the degree of asymmetry in the bipolar magnetic field B z is an important signature for identifying flux transfer events and distinguishing between models.…”

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confidence: 51%

Role of electron physics in the development of turbulent magnetic reconnection in collisionless plasmas

et al. 2011

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Magnetic reconnection releases energy explosively as field lines break and reconnect in plasmas ranging from the Earth's magnetosphere to solar eruptions and astrophysical applications. Collisionless kinetic simulations have shown that this process involves both ion and electron kinetic-scale features, with electron current layers forming nonlinearly during the onset phase and playing an important role in enabling field lines to break 1-4 . In larger two-dimensional studies, these electron current layers become highly extended, which can trigger the formation of secondary magnetic islands 5-10 , but the influence of realistic three-dimensional dynamics remains poorly understood. Here we show that, for the most common type of reconnection layer with a finite guide field, the three-dimensional evolution is dominated by the formation and interaction of helical magnetic structures known as flux ropes. In contrast to previous theories 11 , the majority of flux ropes are produced by secondary instabilities within the electron layers. New flux ropes spontaneously appear within these layers, leading to a turbulent evolution where electron physics plays a central role.Thin current layers are the preferred locations for magnetic reconnection to develop. The most common configuration in nature is guide-field geometry, where the rotation of magnetic field across the layer is less than 180 • . Present theoretical ideas of how reconnection proceeds in these configurations are deeply rooted in early analytical work 11 that, if correct, would imply a direct transition to three-dimensional (3D) turbulence due to a broad spectrum of interacting tearing instabilities. At the core of this idea is the notion that a spectrum of tearing instabilities develops across the initial current sheet for perturbations satisfying the local resonance condition. As these modes grow, the resulting magnetic islands would overlap, leading to stochastic magnetic-field lines and a turbulent evolution. Recently, this type of scenario was proposed as a mechanism for accelerating energetic particles during reconnection 12 . Similar ideas for generating turbulence have been studied in fusion plasmas 13 using resistive magnetohydrodynamics (MHD) and two-fluid 14 models. Alternatively, other researchers have imposed turbulent fluctuations within MHD models in an attempt to understand the consequences 15 . In either case, these results are not applicable to the highly collisionless environment of the magnetosphere, where reconnection is initiated within kinetic ion-scale current layers. The ability to study the self-consistent generation of turbulence during magnetic reconnection with first-principles 3D simulations has only become feasible in the past year.1 Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA, 2 University of California San Diego, La Jolla, California 92093, USA. *e-mail: daughton@lanl.gov. tearing instability gives rise to flux ropes as illustrated by an isosurface of the particle density coloured by the magnitude of the curr...

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“…When such reconnection is localized or non-steady at Earth, discrete magnetic flux tubes with diameters of $1 R E (where 1 R E = 6400 km), termed flux transfer events (FTEs), become connected to the IMF and are pulled from the dayside magnetosphere by the anti-sunward flow in the magnetosheath and added to the tail [Russell and Elphic, 1978]. FTEs created by reconnection occurring simultaneously at multiple dayside X-lines are identified by their flux rope structure [Lee and Fu, 1985]. FTEs not possessing flux rope topology may be produced by short-duration pulses of reconnection [Southwood et al, 1988;Scholer, 1988].…”

Section: Introductionmentioning

confidence: 99%

MESSENGER observations of large flux transfer events at Mercury

Slavin

Lepping

et al. 2010

Geophysical Research Letters

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[1] Six flux transfer events (FTEs) were encountered during MESSENGER's first two flybys of Mercury (M1 and M2). For M1 the interplanetary magnetic field (IMF) was predominantly northward and four FTEs with durations of 1 to 6 s were observed in the magnetosheath following southward IMF turnings. The IMF was steadily southward during M2, and an FTE 4 s in duration was observed just inside the dawn magnetopause followed $32 s later by a 7-s FTE in the magnetosheath. Flux rope models were fit to the magnetic field data to determine FTE dimensions and flux content. The largest FTE observed by MESSENGER had a diameter of $1 R M (where R M is Mercury's radius), and its open magnetic field increased the fraction of the surface exposed to the solar wind by 10-20 percent and contributed up to $30 kV to the cross-magnetospheric electric potential.

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A theory of magnetic flux transfer at the Earth's magnetopause

Cited by 478 publications

References 27 publications

Uv Transient Brightenings Associated With a Coronal Mass Ejection

Uv Transient Brightenings Associated With a Coronal Mass Ejection

Role of electron physics in the development of turbulent magnetic reconnection in collisionless plasmas

MESSENGER observations of large flux transfer events at Mercury

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