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III. APPLICATIONS of RECONNECTION

III. APPLICATIONS of RECONNECTION. 1. Coronal Heating. Yohkoh Bright Pts Loops Holes. A magnetic world T=few MK. Quiet Sun (XRT on Hinode) 30-sec cadence, 12-hour duration. How is the Corona Heated ?. Reconnection: likely cause of coronal heating.

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III. APPLICATIONS of RECONNECTION

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  1. III. APPLICATIONS of RECONNECTION 1. Coronal Heating Yohkoh Bright Pts Loops Holes A magnetic world T=few MK

  2. Quiet Sun (XRT on Hinode)30-sec cadence, 12-hour duration How is the Corona Heated ?

  3. Reconnection: likely cause of coronal heating (i) Drive Simple Recon. at nulls by photc. motions --> X-ray bright point Supported by TRACE (ii) Nanoflares -- Parker Braiding (iii) Modern version: “Coronal Tectonics”(including magnetic carpet)

  4. 2. SOLAR FLARES & CME’s SOHO Coronagraph -- Artificial eclipse Discovered huge ejections of plasma

  5. On October 28, 2003 Photo- sphere [from SOHO] 3rd largest flare

  6. Outer Corona[from SOHO] CME 2000 km/s (5 times faster than normal) Snow -- relc particles

  7. Aurora in St Andrews Thurs

  8. 1 Week Later (Nov 4 )- Fireworks Continued the biggest solar flare ever recorded !

  9. Close-up of plasma motions Conjuring trick -- plasma appearing by magic ?

  10. N.B. • Flare & CME are part of1 magnetic eruptive process • (short MHD connection time) • Difference 2-ribbon flare & CME --- magnetic field strength • Role of filament/prominence -- indicator of high shear So perhaps eruption is driven more from core, where most energy is stored

  11. Overall Picture of Eruption In core - magnetic tube twisted (energy stored in fff) - erupts (catastrophe or breakout) - drives reconnection

  12. Reconnection heats loops/ribbons

  13. (Priest and Schrijver 1999) Reconnection heats loops Continues: new loops form & evaporate. Old loops cool & drain Feet move apart

  14. Examples of prominences

  15. Eruptions:

  16. Ex of Cusped Loops Rising

  17. Example from SOHO

  18. Example from TRACE (171 A) 1 MK (Fe IX) + 20 MK (Fe XVI)

  19. Before: twistedsigmoid --> energy stored

  20. Cause of Eruption ? (i) Magnetic Catastrophe (Priest & Forbes)

  21. (ii) Antiochos et al - breakout model for eruption

  22. Yuhong Fan Emergence of flux rope into a potential arcade Eruption due to magnetic catastrophe when twist > 3.4

  23. Similar model for kink instability, with different flux tube/ overlying field Tibor Torok

  24. 3. CONCLUSIONS • Understanding how B interacts with plasma: Key to many solar system phenomena • Two main equations: Induction equation -- advection + diffusion Eqn. motion -- magnetic tension + pressure forces • Reconnection • different roles in coronal heating, • Solar flares & CMEs

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