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SPD June 16, 2003 Separators: Fault Lines in the Magnetic Field Dana Longcope Montana State University.

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Presentation on theme: "SPD June 16, 2003 Separators: Fault Lines in the Magnetic Field Dana Longcope Montana State University."— Presentation transcript:

1 SPD June 16, 2003 Separators: Fault Lines in the Magnetic Field Dana Longcope Montana State University

2 SPD June 16, 2003 Acknowledgments Graham Barnes Colin Beveridge Steve Cowley Charles Kankelborg Isaac Klapper KD Leka Tetsuya Magara Eric Priest Aad van Ballegooijen Brian Welsch NASA NSF/ATM AFOSR

3 SPD June 16, 2003 The Changing Magnetic Field TRACE 171A 8/10/01 12:51 UT 8/11/01 17:39 UT 8/11/01 9:25 UT (movie)(movie) THE CORONA PHOTOSPHERE SoHO MDI

4 SPD June 16, 2003 Is this Reconnection? 8/10/01 12:51 UT 8/11/01 17:39 UT 8/11/01 9:25 UT (movie)(movie) THE CORONA PHOTOSPHERE TRACE 171A SoHO MDI

5 SPD June 16, 2003 Outline 1.The XBP: A simple example of 3d reconnection 2.Quantifying Reconnection 3.Numerical simulation 4.A more complex example

6 SPD June 16, 2003 Example: X-ray bright points EIT 195A image of “quiet” solar corona

7 SPD June 16, 2003 Example: X-ray bright points Small specks occur above pair of magnetic poles (Golub et al Harvey 1985)

8 SPD June 16, 2003 Example: X-ray bright points

9 SPD June 16, 2003 When 2 Poles Collide Photospheric flux concentrations sources of coronal field

10 SPD June 16, 2003 When 2 Poles Collide All field lines from positive source P1 All field lines to negative source N1

11 SPD June 16, 2003 When 2 Poles Collide Poles approach: domains intersect

12 SPD June 16, 2003 When 2 Poles Collide Reconnection = new field lines

13 SPD June 16, 2003 Post-reconnection Flux Tube TRACE observations 6/17/98 (Kankelborg & Longcope 1999)

14 SPD June 16, 2003 Quantifying Reconnection Why does it release energy? How much energy can it release? What about reconnection in complex magnetic fields?

15 SPD June 16, 2003 Quasi-static Evolution W(x) Equilibrium: W’(x)=0

16 SPD June 16, 2003 Quasi-static Evolution W(x) Equilibrium: W’(x)=0W(x) evolves … SLOWLY

17 SPD June 16, 2003 Equilibrium: Minimum Energy W’(x)=0 potential W(x)  W=W’  x

18 SPD June 16, 2003 Mimimum w/ Constraints Absolute min. –249’ Constrained min. –195’ Constraint curve US 190

19 SPD June 16, 2003 A new type of constraint… Number of field lines linking each pair remains constant (Longcope 2001, Longcope & Klapper 2002) No reconnection Photospheric sources move

20 SPD June 16, 2003 A new type of constraint… Minimize: Subject to flux constraints (Longcope 2001, Longcope & Klapper 2002)

21 SPD June 16, 2003 Separators: where domains meet P2N1 N2P1 Distinct flux domains

22 SPD June 16, 2003 Separators: where domains meet Distinct flux domains Separator at interface

23 SPD June 16, 2003 Separators: where domains meet Distinct flux domains Separator at interface Closed loop encloses all flux linking P2-N1

24 SPD June 16, 2003 The Separator Constraint Closed loop encloses all flux linking P2-N1 P2N1 N2P1 Fluxes in remaining domains: set by BC Constraint only at separator

25 SPD June 16, 2003 Minimum W subj. to constraint Constraint on P2-N1 flux Current-free within each domain current sheet at separator

26 SPD June 16, 2003 Minimum W subj. to constraint 2d version: boundary of 4 domains becomes current sheet Constraint on P3-N2 flux

27 SPD June 16, 2003 Constrained Miniumum 0 W pot W mcc Potential field: absolute min. Min. subject to constraint

28 SPD June 16, 2003 Constrained Miniumum 0 W pot W mcc Potential field: absolute min. Min. subject to constraint Current

29 SPD June 16, 2003 Constrained Miniumum 0 W pot W mcc Min. subject to constraint Free energy Potential field: absolute min.

30 SPD June 16, 2003Reconnection 0 W pot W mcc Potential field: absolute min. Eliminate constraint Min. Energy Drops

31 SPD June 16, 2003 Numerical Test Model: Current sheet in flux-constrained equilibrium Simulation: midplane (Longcope & Magara 2003)

32 SPD June 16, 2003 A complex Example Approximate p-spheric field using discrete sources

33 SPD June 16, 2003 The domain of new flux Emerging bipole P01-N03 New flux connects P01-N07

34 SPD June 16, 2003 Summary 3d reconnection occurs at separators3d reconnection occurs at separators Currents accumulate at separatorsCurrents accumulate at separators  store magnetic energy  store magnetic energy Reconnection there releases energyReconnection there releases energy

35 SPD June 16, 2003 A Case Study TRACE & SOI/MDI observations 6/17/98 (Kankelborg & Longcope 1999) (movie)movie(movie)movie

36 SPD June 16, 2003 Post-reconnection Flux Tube Flux Accumulated over Projected to bipole location

37 SPD June 16, 2003 Post-reconnection Flux Tube Flux Accumulated over

38 SPD June 16, 2003 Numerical Test Initially: potential field Move 2 inner sources slowly Solve 3d MHD eqns. (inside box) (Longcope & Magara 2003)

39 SPD June 16, 2003 Numerical Test (Longcope & Magara 2003)


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