34th Solar Physics Division Meeting, June 2003
Session 1 Corona I
Oral, Monday, June 16, 2003, 9:00am-12:00noon, Auditorium

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[1.01] Magnetic Separators: Fault Lines in the Coronal Field

D.W. Longcope (Montana State University)

Theories have long implicated the process of magnetic reconnection in many aspects of coronal activity. It is, however, difficult to reconcile the simple X-point geometry of classic, two-dimensional reconnection models with the complex appearance of the coronal plasma observed by recent spacecraft such as Yohkoh, TRACE or SOHO. Nor is it surprising that the real corona is so richly structured, given the complexity of the photospheric magnetic field to which it is connected. To understand where and why reconnection occurs in a realistic field, let us assume that coronal field lines interconnect a complex set of distinct, photospheric flux concentrations. A model of quasi-static evolution follows from the assumption that the coronal field remains in a state of minimum magnetic energy while maintaining a given set of connections. This minimum energy field naturally contains a network of current sheets lying on surfaces called magnetic separators, each of which forms the interface of four different interconnections (making it the analog of an X-point current sheet in two dimensions). In this quasi-static model, magnetic reconnection amounts to changing the interconnections of a set of field lines, thereby eliminating one constraint and decreasing the overall minimum energy. The energy difference found from this hypothetical de-constraint provides a lower bound on the free energy available from reconnection in fields of arbitrary complexity. I will present applications of this technique to observed fields ranging in complexity from small X-ray bright points to flaring active regions.


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