FORMATION AND RECONNECTION OF THREE-DIMENSIONAL CURRENT SHEETS IN THE SOLAR CORONA

Journal Article · Tue Jul 20 00:00:00 EDT 2010 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/718/1/72· OSTI ID:21455171

Edmondson, J K ^[1]; Antiochos, S K ^[2]; DeVore, C R ^[3]

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1. NASA Jet Propulsion Laboratory, Pasadena, CA 91109 (United States)
2. NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)
3. Naval Research Laboratory, Washington, DC 20375 (United States)

Current-sheet formation and magnetic reconnection are believed to be the basic physical processes responsible for much of the activity observed in astrophysical plasmas, such as the Sun's corona. We investigate these processes for a magnetic configuration consisting of a uniform background field and an embedded line dipole, a topology that is expected to be ubiquitous in the corona. This magnetic system is driven by a uniform horizontal flow applied at the line-tied photosphere. Although both the initial field and the driver are translationally symmetric, the resulting evolution is calculated using a fully three-dimensional (3D) magnetohydrodynamic simulation with adaptive mesh refinement that resolves the current sheet and reconnection dynamics in detail. The advantage of our approach is that it allows us to directly apply the vast body of knowledge gained from the many studies of two-dimensional (2D) reconnection to the fully 3D case. We find that a current sheet forms in close analogy to the classic Syrovatskii 2D mechanism, but the resulting evolution is different than expected. The current sheet is globally stable, showing no evidence for a disruption or a secondary instability even for aspect ratios as high as 80:1. The global evolution generally follows the standard Sweet-Parker 2D reconnection model except for an accelerated reconnection rate at a very thin current sheet, due to the tearing instability and the formation of magnetic islands. An interesting conclusion is that despite the formation of fully 3D structures at small scales, the system remains close to 2D at global scales. We discuss the implications of our results for observations of the solar corona.

• OSTI ID: 21455171
• Journal Information: Astrophysical Journal, Vol. 718, Issue 1; Other Information: DOI: 10.1088/0004-637X/718/1/72; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
ASPECT RATIO
ASTROPHYSICS
COMPUTERIZED SIMULATION
MAGNETIC ISLANDS
MAGNETIC RECONNECTION
PHOTOSPHERE
SOLAR CORONA
SOLAR SYSTEM EVOLUTION
SUN
SYMMETRY
TEARING INSTABILITY
THREE-DIMENSIONAL CALCULATIONS
TOPOLOGY
TWO-DIMENSIONAL CALCULATIONS
ATMOSPHERES
DIMENSIONLESS NUMBERS
EVOLUTION
INSTABILITY
MAGNETIC FIELD CONFIGURATIONS
MAIN SEQUENCE STARS
MATHEMATICS
PHYSICS
PLASMA INSTABILITY
PLASMA MACROINSTABILITIES
SIMULATION
SOLAR ATMOSPHERE
STARS
STELLAR ATMOSPHERES
STELLAR CORONAE