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Coronal loops formed by separator reconnection: The birth & life of AR9574

Coronal loops formed by separator reconnection: The birth & life of AR9574. Dana Longcope Montana State University. Collaborators:. Jonathan Cirtain Dave McKenzie Jason Scott. MSU. Support:. NASA grant NAG5-10489 Isaac Newton Institute, Cambridge. Outline. What happened in Aug. 2001

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Coronal loops formed by separator reconnection: The birth & life of AR9574

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  1. Coronal loops formed by separator reconnection:The birth & life of AR9574 Dana LongcopeMontana State University

  2. Collaborators: • Jonathan Cirtain • Dave McKenzie • Jason Scott MSU Support: • NASA grant NAG5-10489 • Isaac Newton Institute, Cambridge

  3. Outline • What happened in Aug. 2001 • Cataloging interconnections • Making a magnetic model • Interp’ing data w.r.t. the model • What does it tell us about reconnection

  4. Case study: AR 9574 SoHO MDI SoHO MDI White light Line-of-sight B 2001 Aug 11, 11:15 UT

  5. Case study: AR 9574 SoHO MDI SoHO MDI AR9570 AR9570 White light Line-of-sight B 2001 Aug 11, 11:15 UT

  6. Case study: AR 9574 SoHO MDI SoHO MDI AR9574 AR9574 AR9570 AR9570 White light Line-of-sight B 2001 Aug 11, 11:15 UT

  7. Case study: AR 9574 PHOTOSPHERE AR9574 AR9570 movie 2001-08-10 12:51 UT

  8. Case study: AR 9574 PHOTOSPHERE CORONA 2001-08-10 12:51 UT movie TRACE 171A (106 K Plasma)

  9. The emergence process 2001-08-10 12:51 UT 2001-08-11 17:39 UT white black white black

  10. Timeline of emergence CORONA 7:34 00:00 12:00 00:00 12:00 00:00 Aug 10, 2001 Aug 11, 2001 PHOTOSPHERE

  11. Why this is reconnection Reconnected flux Emerged flux Old flux

  12. Interconnecting loops:A catalog Synthetic slit 5139 images @ 28 sec 7:00 Aug10 – 23:59 Aug11 BG subtracted TRACE 171 images:

  13. 11:00 Stack slit pixels… Time after 00:00 Aug10 Position @ 11:00 Aug10

  14. Loops are bright features

  15. Lots of loops: ~9:00  14:00 Gen’l bright’g 1st loop: 12:36

  16. Finding the loops • Identify peaks • in slit-intensity • loop = fw @ hm

  17. Finding the loops • Identify peaks • in slit-intensity • loop = fw @ hm 25 22 23 26 24

  18. Finding the loops Loop = row of peaks Show peaks vs. time

  19. Finding the loops Verify spatial correspond-ence w/ intercon’ing loops

  20. Interconnecting loops:A catalog 43 loops identified total 1st loop: (probably) interconnects loops 171A intensity loop: definitely interconnects loop flurry ~9:00

  21. Interconnecting loops:A catalog properties of all 43 loops density lower bound

  22. Magnetic Model movie SoHO MDI Identify distinct regions with |Bz| > 45 G

  23. Magnetic evolution

  24. Coronal Field State of least energy: Potential Field

  25. Coronal Field Includes connections AR9574 to AR9570 (P051  N01) …all under separatrix surface

  26. Separatrices enclose loops

  27. Coronal Field Inter-connecting lines enclosed by separator

  28. Coronal Field Inter-connecting flux: P051 AR9574 Potential field: Increasing interconnection

  29. Flux in 171A loops • Assumptions • Each loop is a field-line bundle (flux tube) • Loops/flux tubes : x-section • Loop track flux tube for entire life • No flux tube re-appears in 171 A

  30. Flux in 171 A loops 1. Each loop is a field-line bundle (flux tube)

  31. Flux in 171 A loops Y Flux in pot’l model loops Flux if B0 = 30 G Cummulative loop areas

  32. Reconnection observed Y Flux in pot’l model Incomplete reconnection 24 hour delay Burst of reconnection 1016 Mx/sec = 100 MV

  33. The story of the loops life time  heating density lower bounds radiative cooling time (upper bound on life) RTV equilibria

  34. The story of the loops TRACE 171 A Yohkoh SXT movie ~3,000,000 K 950,000 K Loops are hot (~3MK) after reconnection… Gradually cool into TRACE pass-band (All of them?)

  35. There were no flares Reconnection burst

  36. Model of energy storage Unconstrained minimum: W Wpot Flux Y=Y(v) linking poles 0

  37. Model of energy storage Constrain Flux Y & minimize energy… W Wfce DW Wpot Flux Constrained Equilibrium (Longcope 2002) 0

  38. Model of energy storage Flux Constrained Equilibrium (Longcope 2002) Lowest Energy w/ fixed Y: • Current-free • except …

  39. Model of energy storage Flux Constrained Equilibrium (Longcope 2002) Lowest Energy w/ fixed Y: • Current-free • except … • Current Sheet • @ separator • I(DY) • Mag. Energy • in excess of • potential • DW(DY)

  40. Steady Reconnection? Sweet-Parker: = 4 months

  41. Comparison of scales c/wpi Sweet-Parker: ri

  42. Role(s) of Current Sheet Site of localized reconnection 1018 Mx of newly reconnected flux (1% of DY)

  43. Role(s) of Current Sheet Releases DE ~ I Dy ~ 1028 ergs 1018 Mx of newly reconnected flux (1% of DY)

  44. Role(s) of Current Sheets W Energy storage: W accumulates for 24 hrs. prior to reconn’ burst Wfce DW Wpot Rapidly released via local process 0

  45. Summary • AR 9574: Example of reconnection between new & old active regions • Reconnection occurs in brief (6 hour) burst after delay of ~24 hours • Produces dozens of ~1018 Mx loops • Observed flux accounts for 10% - 30% of maximum allowed (partial reconn.)

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