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Session 2 - Everything Else.
Display session, Friday, June 27
Ballroom C, Chair: Richard Canfield

[2.60] On the Dynamics of Magnetic Flux Concentrations in Quiet Photospheric Network.

J. I. Sakai (Toyama University), M. Ryutova (Stanford University), K. Schrijver, R. Shine, T. Tarbell, T. Berger, A. Title (LMPARL), H. Hagenaar (University of Utrecht, The Netherlands)

Magnetic flux concentrations in the quiet photospheric network show a complex dynamics which includes merging of colliding fluxes, the "total" or partial cancellation of neighboring fluxes, fragmentation and others. We propose a mechanism to explain the observed phenomena based on the idea that magnetic flux concentrations in the photospheric network are essentially non-collinear. We show that non-collinearity of colliding fluxes leads to the whole new class of effects which are observed; for example, the apparent cancellation of opposite polarity fluxes turns into the formation of horizontal magnetic fluxes (which later may appear as a new weaker bipoles) and is accompanied by the shock formation and mini-flares. In the case of shock formation the reconnection area becomes a source of the acoustic emission; mini-flares may be seen as bright points. The energetics of these processes strongly depends on geometry of "collision" and physical parameters of colliding fluxes. For example, if colliding fluxes have comparable and "small" cross sections, the reconnection results in complete reorganization of their magnetic fields; if merging fluxes are large enough or considerably different, magnetic flux may be only partially reconnected and partially survived. Reconnection of non-collinear equal polarity fluxes leads to the "scattering" processes which include the fragmentation into several smaller fluxes if initially colliding concentrations carried different amount of magnetic flux. We give the example of numerical simulation for the case of merging and fragmentation process occurring during the collision of collinear "strong" and "weak" magnetic flux concentrations. The calculation results shown to be consistent with observational data from both the SOHO/MDI instrument and the Swedish Vacuum Solar Telescope on La Palma.

This research is supported by NASA contract NAG5-3077 at Stanford University and the MDI contract PR 9162 at Lockheed.

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