Interchange reconnection in a turbulent Corona

Abstract

Magnetic reconnection at the interface between coronal holes and loops, so-called interchange reconnection, can release the hotter, denser plasma from magnetically confined regions into the heliosphere, contributing to the formation of the highly variable slow solar wind. The interchange process is often thought to develop at the apex of streamers or pseudo-streamers, near Y and X-type neutral points, but slow streams with loop composition have been recently observed along fanlike open field lines adjacent to closed regions, far from the apex. However, coronal heating models, with magnetic field lines shuffled by convective motions, show that reconnection can occur continuously in unipolar magnetic field regions with no neutral points: photospheric motions induce a magnetohydrodynamic turbulent cascade in the coronal field that creates the necessary small scales, where a sheared magnetic field component orthogonal to the strong axial field is created locally and can reconnect. We propose that a similar mechanism operates near and around boundaries between open and closed regions inducing a continual stochastic rearrangement of connectivity. We examine a reduced magnetohydrodynamic model of a simplified interface region between open and closed corona threaded by a strong unipolar magnetic field. This boundary is not stationary, becomes fractal, and field lines change connectivity continuously, becoming alternatively open and closed. This model suggests that slow wind may originate everywhere along loop-coronal hole boundary regions, and can account naturally and simply for outflows at and adjacent to such boundaries and for the observed diffusion of slow wind around the heliospheric current sheet.

6 pages, 5 figures, 1 movie, ApJ Letters (accepted)

References in corpus (8)

• Self-consistent Coronal Heating and Solar Wind Acceleration from Anisotropic Magnetohydrodynamic Turbulence
• A Model for the Sources of the Slow Solar Wind
• Establishing a Connection Between Active Region Outflows and the Solar Wind: Abundance Measurements with EIS/Hinode
• Magnetic Topology of Coronal Hole Linkages
• Coronal Heating, Weak MHD Turbulence and Scaling Laws
• Structure and Dynamics of the Sun's Open Magnetic Field
• Interchange Slip-Running Reconnection and Sweeping SEP Beams
• Diamagnetic and Expansion Effects on the Observable Properties of the Slow Solar Wind in a Coronal Streamer

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• Formation and Reconnection of Three-dimensional Current Sheets with a Guide Field in the Solar Corona
• Interchange reconnection associated with a confined filament eruption: Implications for the source of transient cold-dense plasma in solar winds
• Coronal Heating Topology: the Interplay of Current Sheets and Magnetic Field Lines
• The S-Web Origin of Composition Enhancement in the Slow-to-Moderate Speed Solar Wind
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• Homologous compact major blowout-eruption solar flares and their production of broad CMEs
• Inward Propagating Plasma Parcels in the Solar Corona: Models with Aerodynamic Drag, Ablation, and Snowplow Accretion