THREE-DIMENSIONAL SIMULATIONS OF TEARING AND INTERMITTENCY IN CORONAL JETS

ABSTRACT Observations of coronal jets increasingly suggest that local fragmentation and intermittency play an important role in the dynamics of these events. In this work, we investigate this fragmentation in high-resolution simulations of jets in the closed-field corona. We study two realizations o...

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Bibliographic Details
Published in:The Astrophysical journal 2016-08, Vol.827 (1), p.4-4
Main Authors: Wyper, P. F., DeVore, C. R., Karpen, J. T., Lynch, B. J.
Format: Article
Language:English
Subjects:
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
DENSITY
Ejection
EMISSION
FRAGMENTATION
Fragments
INSTABILITY
Intermittency
Jets
LAYERS
MAGNETIC FIELDS
Magnetic flux
MAGNETIC RECONNECTION
Outflow
RESOLUTION
SIMULATION
SUN
Sun: activity
Sun: corona
Sun: flares
Sun: magnetic fields
SURFACES
Tearing
THREE-DIMENSIONAL CALCULATIONS
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Summary:ABSTRACT Observations of coronal jets increasingly suggest that local fragmentation and intermittency play an important role in the dynamics of these events. In this work, we investigate this fragmentation in high-resolution simulations of jets in the closed-field corona. We study two realizations of the embedded-bipole model, whereby impulsive helical outflows are driven by reconnection between twisted and untwisted field across the domed fan plane of a magnetic null. We find that the reconnection region fragments following the onset of a tearing-like instability, producing multiple magnetic null points and flux-rope structures within the current layer. The flux ropes formed within the weak-field region in the center of the current layer are associated with "blobs" of density enhancement that become filamentary threads as the flux ropes are ejected from the layer, whereupon new flux ropes form behind them. This repeated formation and ejection of flux ropes provides a natural explanation for the intermittent outflows, bright blobs of emission, and filamentary structure observed in some jets. Additional observational signatures of this process are discussed. Essentially all jet models invoke reconnection between regions of locally closed and locally open field as the jet-generation mechanism. Therefore, we suggest that this repeated tearing process should occur at the separatrix surface between the two flux systems in all jets. A schematic picture of tearing-mediated jet reconnection in three dimensions is outlined.
ISSN:0004-637X
1538-4357
DOI:10.3847/0004-637X/827/1/4