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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. Observations of Reconnection.

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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. Observations of Reconnection Flare (Sweet) Jet (Shimojo & Shibata) CME (Lin & Forbes)

  4. Outline Flux Emergence: A new setting for studying reconnection • 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

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

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

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

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

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

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

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

  12. Why this is reconnection Reconnected flux Emerged flux Baum & Bratenahl 1976 Old flux

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

  14. 11:00 Stack slit pixels… Time after 00:00 Aug10 Position @ 11:00 Aug10

  15. Loops are bright features

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

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

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

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

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

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

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

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

  24. Magnetic evolution

  25. Coronal Field State of least energy: Potential Field

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

  27. Separatrices enclose loops

  28. Coronal Field Inter-connecting lines enclosed by separator

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

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

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

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

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

  34. P-spheric Trigger? Response? 24 hour delay loop flurry ~9:00

  35. There were no flares Reconnection burst

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

  37. 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?)

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

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

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

  41. 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)

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

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

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

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

  46. 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

  47. Summary • AR 9574: unambiguous reconnection • Reconnection in brief (6 hour) burst after delay of ~24 hours • Separator reconnection • Trigger? … No evidence in p-sphere • Produces scores of ~1018 Mx loops • Observed flux accounts for 10% - 30% of maximum allowed (partial reconnection)

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