1. Imaging Solar Coronal Structure With TRACE Leon Golub, SAO TRACE:http://vestige.lmsal.com ISAS - 4 Feb. 2003

2. The SAO Solar-Stellar X-ray Group Leon Golub Jay Bookbinder Ed DeLuca Mark Weber Joe Boyd Paul Hamilton Dan Seaton With results from A. Van Ballegooijen, A. Winebarger and H. Warren http://hea-www.harvard.edu/SSXG/

3. The Major Coronal Physics Problems 1. Why is the corona hot? 2. Why is the corona structured? 3. Why is the corona dynamic & unstable? Emergence of B into the atmosphere, and response to B.

4. Why Use X-rays to Observe Corona?

5. Response to flux emergence 1. Vigorous EFR Dynamics. 2. Large-scale B adjustment. 3. Strong local heating. (30-second cadence for 24 hours)

6. Outline of Talk “Loops”: What TRACE sees: a. Non-hydrostatic loop controversy: what are we really seeing? b. Moss and transient vs. steady heating. c. Hot vs. cool material in ARs

7. Heating & Dynamics in ARs TRACE sees four (or possibly only three) distinct processes in active regions: 1. Steady outflows in long, cool structures. ◄ 2. Transient loop brightenings in emerging flux areas. Also hot & cool material intertwined – May or may not be related to TLBs. 3. Steady heating of hot loops (moss). ◄ 4. Flare-like events at QSLs (or may be cooling events predicted by 3.).

8. Examples of all four phenomena

9. Another example of flows

10. Same region – next day (ignore the little flares nearby!)

11. 11 TRACE Active Region Observations are not Consistent With Hydrostatic Model Figure from Aschwanden et al. 2000

12. 12 Non-HS Loops are ubiquitous courtesy H. Warren

13. Partial Listing of Recent Papers About Non-Hydrostatic Loops Lenz etal 1999, ApJ, 517, L155. Aschwanden etal 2000, ApJ, 531, 1129. Winebarger etal 2001, ApJ, 553, L81. Schmelz etal 2001, ApJ, 556, 896. Chae etal 2002, ApJ, 567, L159. Testa etal 2002. ApJ, 580, in press. Martens etal 2002, ApJ, 577, L115. Schmelz 2002, ApJ, 578, L161. Aschwanden 2002,ApJ, 580, L79. Warren etal 2003, ApJ, submitted. Small gradient in filter ratio, high n. Multithread model (a la Peres etal 1994, ApJ 422, 412), footpoint heating. Flows and transient events in non-hydrostatic loops. DEM spread → const. filter ratio. More passbands may help. Large range in thread T for some loops. Full DEM need at each point. Grad T along loops w/flat filter ratio Contra Martens. Repeated heating episodes.

14. What Needs to be Explained? 1. 195A/173A ratio is flat. 2. Emission extends too high for hydrostatic loop (this is debated, though). 3. Loop density is high by an order of magnitude. 4. Apparent flows (and some Doppler shifts measured).

15. Active Region 8536

16. How isothermal are these loops?

17. 17 SUMER Velocities

18. Symmetric vs. Asymmetric Heating

20. Static vs. Flow Model Winebarger etal ApJL (2001)

21. 21 Best fit vs. Uniform heating

22. High-Conductance Model with Asymmetric Heating

23. The Effect of High Conductivity

24. Footpoints in Transient Heating 1. Initial energy release along current sheet (“spotty”) 2. Footpooint brightening. 3. Evaporation, then post-flare loops.

27. Comparison: Evaporative Model vs.TRACE Obs.

30. Moss as TR of Hot Loops

33. Heating Shut-off vs. Observations

34. Using FLASH to model coronal loops FLASH is a state-of-the-art simulator code for solving thermonuclear/astrophysical problems. FLASH is funded under the DoE ASCI/Alliances Program. SAO study of coronal loops with FLASH is in collaboration with the Palermo Astronomical Observatory, with technical support from the FLASH Center.

35. FLASH: The coronal loop application One-dimensional, vertical, semicircular loop with half-length of 100 Mm Boundary conditions: T = 20,000 K; n e = ~10 10 Hydrodynamic model: ionized hydrogen plasma; gravity; Spitzer conductivity; and radiative cooling (Raymond & Smith, 1977; Raymond, 1978)

36. Stability regime diagram: Asymmetric footpoint heating scale height vs. loop length Solution points from a code by van Ballegooijen (not published). The corresponding results for symmetric heating give a virtually identical stability boundary. For comparison, the plotted lines indicate the stability thresholds predicted for symmetric footpoint heating. The van Ballegooijen results (for both symmetric and asymmetric heating) are more consistent with the Serio et al. line. The boxes indicate stable, converged FLASH trial solutions. The leftmost box is not consistent with the van Ballegooijen results. Steady-state regime Unstable regime

37. FLASH solution, point #1: s H = 39.8 Mm Steady siphon flow Initial condition: corresponding steady-state solution from van Ballegooijen’s code

38. FLASH solution, point #2: s H = 25.1Mm Steady siphon flow Initial condition: corresponding steady-state solution from van Ballegooijen’s code

39. FLASH solution, point #3: s H = 15.8 Mm Steady siphon flow Initial condition: steady-state solution from van Ballegooijen’s code for point #2, because… van Ballegooijen’s code does not converge to a steady-state solution for point #3, in contrast to FLASH, which does reach steady-state

40. Further work with FLASH Currently running more solution points in sequence shown on stability plot in order to locate the instability threshold for a loop with half-length 100 Mm. We are collaborating with the Palermo Astronomical Observatory to investigate dynamic behavior of both symmetrically and asymmetrically heated loops. Q: will we be able to reproduce observed non- linear behaviors of hot and cool material flowing together in TRACE active region loops?

41. Microscale B vs. X 1. Complex relation between photosphere and corona. 2. Very rapid dynamics. 3. Large T-range to be observed. Resolution requires Solar-B observations!

42. New View of Coronal Structures β»1 +  + Hot Plasma

43. Hot Material in the Corona Mg XII Ly-α superposed on Fe X (log T = 6.9 and 6.0) Consistent with RHESSI detection of non-thermal electrons in “quiescent” active regions.

44. TRACE Flare Results TRACE observes Fe XXIV 192 Å – highest resolution images ever of hot flare plasma Qualitatively consistent with flare models – hot loops form first, cool post-flare loops form later Evidence for “hot” regions – 20 MK plasma is found above 10 MK flare arcades Fine structure in flares – simulations with many small loops are needed to reproduce the observations Pre-Flare observations – evolution of ribbon brightenings is complex

45. A Typical Event

46. July 25, 1999 M2.4 Limb Flare Warren etal., ApJLett, 1999.

47. Most of the Flare Emission is Near 10 MK: June 25, 1999 M2.4

48. SXT and TRACE Show 15-20 MK Loop-Top Plasma

49. March 24, 2000 X1.8 Flare: 1600 Å and 195 Å Movies Warren & Reeves, ApJLett (2000).

50. March 24, 2000 X1.8 Flare: 195 Å Near SXR Peak

51. March 24, 2000 X1.8 Flare: 195/171 Filter Ratios

52. Reconnection at top of flares 1. Flare heating is preceded by expansion of high loops. 2. Hi-T source above postflare loops.  3. Hi-T coincident with footpoint ribbon heating. 4. Source moves upward during course of flare. 

53. Modeling the Evolution of the Flare Arcade (2D)

54. Comparisons With Simulation: TRACE 195/171 Filter Ratios

55. Improved Fit with Taller Loops

56. END PRESENTATION

57. March 17, 2000 M1.1: TRACE 1600 Å Movie Warren & Warshall,ApJL (2001)

58. March 17, 2000 M1.1: TRACE 1600 Å Images

59. March 17, 2000 M1.1: TRACE 1600 Å Light Curves

60. TRACE Footpoint vs. BATSE HXR →HESSI!

61. The Solar-B Mission

62. The Solar-B Instrument Complement 1. Solar Optical Telescope with Focal Plane Package (FPP) - 0.5m Cassegrain, 480-650nm - VMG, Spectrograph - FOV 164X164 arcsec 2. EUV Imaging Spectrograph (EIS) - Stigmatic, 180-204, 240-290Å - FOV 6.0X8.5 arcmin 3. X-ray Telescope (XRT) - 2-60Å - 1 arcsec pixel - FOV 34X34 arcmin

63. XRT vs. SXT Comparison 1. Higher spatial resolution: 1.0” vs. 2.5” 2. Higher data rate: 512kB continuous. 3. Ten focal plane analysis filters. 4. Extended low-T and high-T response. 5. FIFO buffer for flare-mode obs.

65. 65 Science Themes Plasma Dynamics Thermal Structure and Stability The Onset of Large Scale Instabilities Non-Solar Objects

66. 66 Plasma Dynamics Reconnection –loop-loop interaction –flux emergence –nano-flares –AR jets –macro-spicular jets –filament eruption

67. 67 Plasma Dynamics Waves –origin of high speed wind –tube waves –coronal seismology Figures from Nakariakov et al. (1999): decaying loop oscillations seen in TRACE can be used to estimate the coronal dissipation coefficient. R e ~ 6 x 10 5 or R m ~ 3 x 10 5, about 8 orders of magnitude less than classical values.

68. 68 Thermal Structure/Stability Physical Properties –Te, ne, EM –energetics –variability timescales Multithermal Structure –steady loops –filaments

69. 69 Onset of Large Scale Instabilities Emerging Flux Region –twisting/untwisting –reconnection delta Spots –current sheets –topology changes Active Filaments –T e, n e –local heating

70. 70 Non-Solar Objects Jupiter –S VII @ 198 Nearby RS Cvns Galaxy Cluster Halos Comets Any EUVE source within 1 deg of Sun

71. Science Drivers I: Spatial Scales “Global” MHD Scales – Active Regions; – granulation scales Transverse scales  n  B  and j Reconnection sites –location –size –dynamics 10 5 km 10 3 km 10 1 - 10 3 km <10 km RAM discovery space

72. Science Drivers II: Time Scales Loop Alfven time Sound speed vs. loop length Ion formation times Plasma instability times Transverse motions Surface B evolution times ~10 sec ~100 sec ~1 - 10 sec ~10 - 100 sec 1 - 100 sec minutes - months

73. Optics Metric