NUMERICAL EXPERIMENTS ON FINE STRUCTURE WITHIN RECONNECTING CURRENT SHEETS IN SOLAR FLARES

Journal Article · Wed Aug 10 00:00:00 EDT 2011 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/737/1/14· OSTI ID:21579999

Chengcai, Shen; Jun, Lin ^[1]; Murphy, Nicholas A ^[2]

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1. Yunnan Astronomical Observatory, Chinese Academy of Sciences, P.O. Box 110, Kunming, Yunnan 650011 (China)
2. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

We perform resistive magnetohydrodynamic simulations to study the internal structure of current sheets that form during solar eruptions. The simulations start with a vertical current sheet in mechanical and thermal equilibrium that separates two regions of the magnetic field with opposite polarity which are line-tied at the lower boundary representing the photosphere. Reconnection commences gradually due to an initially imposed perturbation, but becomes faster when plasmoids form and produce small-scale structures inside the current sheet. These structures include magnetic islands or plasma blobs flowing in both directions along the sheet, and X-points between pairs of adjacent islands. Among these X-points, a principal one exists at which the reconnection rate reaches maximum. A fluid stagnation point (S-point) in the sheet appeared where the reconnection outflow bifurcates. The S-point and the principal X-point (PX-point) are not co-located in space though they are very close to one another. Their relative positions alternate as reconnection progresses and determine the direction of motion of individual magnetic islands. Newly formed islands move upward if the S-point is located above the PX-point, and downward if the S-point is below the PX-point. Merging of magnetic islands was observed occasionally between islands moving in the same direction. Reconnected plasma flow was observed to move faster than blobs nearby.

• OSTI ID: 21579999
• Journal Information: Astrophysical Journal, Vol. 737, Issue 1; Other Information: DOI: 10.1088/0004-637X/737/1/14; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
FINE STRUCTURE
INSTABILITY
MAGNETIC FIELDS
MAGNETIC ISLANDS
MAGNETIC RECONNECTION
MAGNETOHYDRODYNAMICS
SIMULATION
SOLAR FLARES
STAGNATION POINT
FLUID MECHANICS
HYDRODYNAMICS
MAGNETIC FIELD CONFIGURATIONS
MECHANICS
SOLAR ACTIVITY
STELLAR ACTIVITY
STELLAR FLARES