2. Palermo October 10, 2005 1 Flare observations in the recent solar maximum H.S. Hudson Space Sciences Lab, UC Berkeley

3. Palermo October 10, 2005 2 Organization of talk Background Major new observational results on flares Modern analysis trends Personal advertisements

4. Palermo October 10, 2005 3 PERSONAL ADVERTISEMENTS Shared topics: hard X-rays; models Research topic #1: white-light flares Research topic #2: the solar radius Other topics: two lines of “science nuggets” and the Solar Flare Cartoon Archive

5. Palermo October 10, 2005 4 Solar physics is no longer the only branch of astrophysics in which movies can be considered to be data…

6. Palermo October 10, 2005 5 Schema (inspired by R. Genzel) Object: Galactic Center Astronomer’s view: Black hole! Astrophysicist’s view: We can learn about relativity, gravity, etc in a new environment! Object: Solar Flare Astronomer’s view: Magnetic reconnection! Astrophysicist’s view: We can learn about plasma behavior in a new environment!

7. Palermo October 10, 2005 6 What is the solar corona? Low-beta plasma in a concentric cavity Slowly-varying lower boundary condition imposing vertical currents Body currents (and current sheets) in an electrically isopotential volume Massive solar wind forming a lumpy upper boundary Flaring (flares and CMEs)

8. Palermo October 10, 2005 7 What is the solar corona? Low-beta plasma in a concentric cavity Slowly-varying lower boundary condition imposing vertical currents Body currents (and current sheets) in an electrically isopotential volume Massive solar wind forming a lumpy upper boundary Flaring (flares and CMEs)

9. Palermo October 10, 2005 8 G. A. Gary, Solar Phys. 203, 71 (2001) (v A ~ 200  -1/2 km/s at coronal temperatures) CH Distribution of coronal plasma 

10. Palermo October 10, 2005 9 Yohkoh, RHESSI, TRACE and ground-based data: 5 recent wonders and marvels

11. Palermo October 10, 2005 10 Movie of dimming (Aug 28, 1992) (1) Coronal Dimming

12. Palermo October 10, 2005 11 TRACE 1600A TRACE 171A Shrinkage, dimming, destruction, oscillation Helix, ribbons (separatrices?)

13. Palermo October 10, 2005 12 (2) RHESSI  -ray imaging

14. Palermo October 10, 2005 13 2 -1.79x10 20 Mx -1.02x10 20 Mx +1.91x10 20 Mx +0.19x10 20 Mx +0.63x10 20 Mx -0.27x10 20 Mx I II III IV V VI Courtesy Y.H. Yang; cf H.M. Wang et al., ApJ 576, 497 (2002) (3) MAGNETIC FIELD CHANGES X-ray Flare

15. Palermo October 10, 2005 14 Field changes are now observed with essentially every X-class flare, and they match the flare ribbon locations Survey of 15 flares by Sudol & Harvey (2004)

16. Palermo October 10, 2005 15 Note that the B field changes correspond with the impulsive phase, GOES rise to maximum

17. Palermo October 10, 2005 16 (4) BOLOMETRIC DETECTION OF SOLAR FLARES (Kopp et al. 2004)

18. Palermo October 10, 2005 17 Dennis et al., 2005

19. Palermo October 10, 2005 18 If these SEPs are accelerated by CME-driven shocks, they use a significant fraction of the shock kinetic energy (~3% to 20%) (Mewaldt et al., 2005; see also Emslie et al. 2005).

20. Palermo October 10, 2005 19 (5) Microflares and jets

21. Palermo October 10, 2005 20 One month of RHESSI microflare observations (2003) Map of ~2000 flare locations of tiny flares seen by RHESSI (microflares) RHESSI microflares take place in active regions Rauscher et al. 2004

22. Palermo October 10, 2005 21 Six months of RHESSI microflare observations (2004) Map of ~3500 flare locations of tiny flares seen by RHESSI (microflares) RHESSI microflares take place in active regions even towards solar minimum Christe & Hannah, 2005

23. Palermo October 10, 2005 22 Imaging the bremsstrahlung from type III burst electrons?

24. Palermo October 10, 2005 23 Two analysis directions: 1. Timewise development of magnetic reconnection

25. Palermo October 10, 2005 24

26. Palermo October 10, 2005 25 Bogachev et al., ApJ 630, 561 (2005) Study of HX footpoint motions I II I. Motion away from NL: 13% II. Shear motion: 26% III. Parallel motion: 35%

27. Palermo October 10, 2005 26 Bogachev et al., ApJ 630, 561 (2005) Study of HX footpoint motions I II I. Motion away from NL: 13% II. Shear motion: 26% III. Parallel motion: 35% Unpredicted!

28. Palermo October 10, 2005 27 Why is the footpoint motion so important? The HXR footpoints show the photospheric anchors of the coronal field. They thus map to the energy source of the flare The motion of the footpoints measures the rate and direction of magnetic reconnection, hence maybe identifying the mechanism

29. Palermo October 10, 2005 28 Evidence for a large-scale coronal current sheet? Sui & Holman, 2004 Anzer & Pneuman, 1982

30. Palermo October 10, 2005 29 First “modern” flare cartoon (Hirayama, 1974)

31. Palermo October 10, 2005 30 MDI magnetic artifacts

32. Palermo October 10, 2005 31 “Opacity minimum” flare IR (1.56  ) (Xu et al., 2004)

33. Palermo October 10, 2005 32 Apparent source motion correlates with energy release (Krucker et al., 2003)

34. Palermo October 10, 2005 33 Deposited Energy vs Footpoint Separation Mar 18, 2003 From Magnetogram: B fp  500 G Assume: B corona  B fp /5 A r = L h ·L v  360 arcsec 2 Perpendicular motion From HXR image: L h  5-10 arcsec  L v  36-72 arcsec (lower limit !!)

35. Palermo October 10, 2005 34 Reconnection electric field Given a large-scale reconnection geometry, one can calculate E = v x B and find it to be of order v/cm (eg, Kopp & Poletto 1984) This field, if it exists, is unidirectional and does not explain double footpoints It is necessary to understand the microscopic plasma physics during reconnection

36. Palermo October 10, 2005 35 Good news: We can estimate the V x B electric field, and it is very large (> v/cm). Bad news: A V x B electric field electric field won’t accelerate particles, since it is perpendicular to B and the particles don’t gain energy directly. cf. Litvinenko, Solar Phys. 212, 379 (2003) and references cited there

37. Palermo October 10, 2005 36 2. The “collapsing trap”

38. Palermo October 10, 2005 37 Shrinking magnetic field? Sui & Holman 2004 Veronig et al. (2005) now have ~5 RHESSI events

39. Palermo October 10, 2005 38 “Isomagnetobars” Before After Hudson cartoon from Archive

40. Palermo October 10, 2005 39 “Collapsing trap” - Karlicky & Kosugi, 2004

41. Palermo October 10, 2005 40 “Collapsing trap” - Aschwanden, 2004

42. Palermo October 10, 2005 41 LATE PHASE ACCELERATION X17 flare of 2005 Sept. 7 17:17 UT (courtesy S. Krucker) cf. Qiu et al. 2004

43. Palermo October 10, 2005 42 A “Collapsing Trap” analysis may help to understand both for the thermal plasma (the flare loops) and also for the non-thermal particles.

44. Palermo October 10, 2005 43 Coronal magnetic field Quantitative before/after magnetic models Aly conjecture Use of images (“data assimilation”) Problems - focusing the energy, accelerating particles, launching shock What is the eigenmode structure of an active region?

45. Palermo October 10, 2005 44 SUMMARY There have been many new solar flare results in the past (current?) maximum New analysis directions are beginning, with some surprises Another new wave of solar spacecraft is coming: Solar-B, STEREO, SDO. Alas, no HXR; double alas, no X-ray spectroscopy

46. Palermo October 10, 2005 45 PERSONAL ADVERTISEMENTS Shared topics: hard X-rays; models Research topic #1: white-light flares Research topic #2: the solar radius Other topics: two lines of “science nuggets” and the Solar Flare Cartoon Archive

47. Palermo October 10, 2005 46 WHITE-LIGHT FLARES TRACE observations, 2004 July 22 n.b. TRACE “white-light” response includes the UV, hence most of the flare luminosity “White light”Difference (reversed) UV 1700A

48. Palermo October 10, 2005 47 SOLAR RADIUS

49. Palermo October 10, 2005 48 CARTOONS

50. Palermo October 10, 2005 49 NUGGETS

51. Palermo October 10, 2005 50 End http://sprg.ssl.berkeley.edu/~tohban/nuggets http://solarmuri.ssl.berkeley.edu/~hudson/cartoons http://sprg.ssl.berkeley.edu/~tohban/nuggets http://solarmuri.ssl.berkeley.edu/~hudson/cartoons