Coronal Mass Ejections: Kinematic Evolution

1. August 3, 2006Sci. & Tech. Univ. China Hefei Coronal Mass Ejections: Kinematic Evolution Jie Zhang George Mason University

2. Outline • Space Weather Program at GMU • Overview of Space Weather • CMEs: kinematic evolution • CMEs, Flares and Magnetic Reconnection • Discussion

3. Space Weather Program at GMU • George Mason University: 30,000 students, the largest in Virginia • Suburb of Washington D.C., close to NASA/GSFC, NRL, APL, UMD APL Capital Hill GSFC GMU NRL

4. Space Weather Program at GMU • Strategy: a system approach to address the integrated Sun-Earth connected system, and heliospher at large. • Initiated in 2003 • Faculty • Dr. Ken Dere (Sun) • Dr. Bob Meier (Ionosphere) • Dr. Merav Ophere (Heliosphere, Sun) • Dr. Art Poland (Sun) • Dr. Bob Weigel (Magnetosphere) • Dr. Jie Zhang (Sun, Heliosphere) • Postdoctoral and Graduate Students

5. Research Highlights • Sun-Earth Connection: CME, ICME and Geomagnetic Storms (Jie Zhang) • CME Initiation and Acceleration (Jie Zhang) • SEEDS (Solar Eruptive Event Detection System) (Jie Zhang)

6. Research Highlights • Heliospheric Modeling (Merav Opher) • ICME and Shock propagation Modeling (Merav Opher)

7. Research Highlights • Coronal heating -- Art Poland • Measurements from SOHO data • Modeling

8. Research Highlights • CHIANTI database (Ken Dere) • CME

9. Research Highlights • ViRBO (Virtual Radiation Belt Observatory) (Bob Weigel) • CISM-DX • TSDS

10. Research Highlights • Ionosphere and Thermosphere (Bob Meier) • I-T system responds to solar & geomagnetic forcing • Develop methods to image the global system • Improve empirical and first principles models

11. Space Weather: the Effects Human Space Exploration Aviation Satellite Operation Power Imagination Communication and Navigation

12. Space Weather: Physical Systems

13. Space Weather: the Connection Courtesy of Manchester Courtesy of Odstrcil

14. Space Weather: the Driver Eruptions caused by magnetic activities Credit: NASA

15. Coronal Mass Ejections: Kinematic Evolution

16. Tracking Evolution EIT: disk to 1.5 Rs C1: 1.1 to 3.0 Rs C2: 2.0 to 6.0 Rs C3: 4.0 to 30 Rs

17. Evolution: Outer Corona Outer corona, ~ constant speed e.g., > 2 Rsun by LASCO C2/C3 Height Time Velocity Time

18. Evolution: Inner Corona Inner corona: fast acceleration e.g., < 2 Rs by LASCO C1 or MK4 Height Time Velocity Time

19. Example: 1998 June 11 event C1: 15 images C2: 3 images C3: 8 images GOES X-ray Flare: C1.1 (Zhang Jie et al., 2001, 2004)

20. Example: 1997 Sep. 20 event C1: 8 images C2: 3 images C2.3 flare C3: 7 image

21. Example: 1996 Oct. 05 event C1: 3 images C2: 3 images Flare: Not in NOAA catalog; A1.2 C3: 7 image

22. Complete Kinematic Evolution CME Flare (Soft X-ray) Phase 1 ---- Initiation Phase---- Pre-flare Phase Phase 2 ---- Acceleration Phase ---- Rise Phase Phase 3 ---- Propagation Phase----Decay Phase CME Velocity Flare Soft X-ray Flux Onset 2 Onset 1 Peak Gallagher et al. 2003 Qiu et al. 2004 Kundu et al. 2004 Sterling & Moor 2005 Phase 1 Phase 2 Phase 3 Time Zhang et al. 2001 Zhang et al. 2004

23. Statistical Study: Accelerations Zhang Jie et al. 2006 (ApJ Oct. Issue)

24. Event Selection • We have systematically examined all LASCO C1 images, about 100,000 images in total from 1996 January to 1998 June • Online event catalog at http://solar.scs.gmu.edu/research/cme_c1/index.html • 50 events in this study, showing evolution in both inner and outer corona • Calculating main acceleration: • Direct method • Indirect method: using flare rise time as proxy of CME main acceleration time

25. Source Regions All close to the limb

26. Main and Residual Acceleration Distribution

27. Main and Residual Acceleration Distribution Main Residual

28. Duration of Main Acceleration

29. Inverse Correlation Between Magnitude and Duration A = 10000 X T-1 (m/s2) (min) The fitting line corresponds to the equal velocity of 600 km/s Magnitude Duration

30. Discussion: 1 • CME main acceleration in the inner corona has a broad distribution, from several m/s2 to several thousand m/s2, with a median value at 170 m/s2. • Continuous distribution of CME acceleration and velocity, which does not support the idea of two distinct classes of CMEs • Description of two classes is only a convenience to refer to different events (Sheeley et al. 1999, Andrew & Howard 2000, Moon et al. 2002, Zhang Mei et al. 2002)

31. CME, Flare and Magnetic Reconnection 1996 to 2005 CME: 10507 Flare: 21347 X-class: 122 M-class: 1418 C-class: 12922 B-class: 6872 A-class: 7 • Most CMEs (~90%) are accompanied by flares • Except extremely gradual CMEs • 75% flares are confined, not associated with CMEs • 5% X-class • 40% M-class (Andrews 2004)

32. CME, Flare and Magnetic Reconnection • Flares are believed to be caused by magnetic reconnection • Almost all impulsive CMEs are associated with flare • What is the role of magnetic reconnection in CME: • acceleration phase ? and • initiation phase ?

33. Magnetic Reconnection • In CME initiation phase, there is no X-ray flare, or very weak enhancement at best • Magnetic reconnection plays an insignificant role in this phase, if any.

34. Magnetic Reconnection • In acceleration phase, magnetic reconnection plays an active role. • The temporal coincidence, between CME acceleration and flare energy release, suggests an active role • The reconnection is not merely the consequence of the catastrophic loss of equilibrium of large scale eruption of coronal magnetic field

35. Magnetic Reconnection • The acceleration of CME-associated TRACE EUV ejector also coincides with the GOES X-ray flare rise phase. (Gallagher et al 2003)

36. Magnetic Reconnection • CME-associated filament acceleration, two-ribbon separation also temporally correlate with the flare main phase (Qiu et al 2004)

37. CME-flare spatial relation • There were strong arguments against that flare-reconnection drives CME, based on • Temporal disparity (proven wrong due to inappropriate linear extrapolation) • Spatial disparity, flare not underneath the center of CME span (Harrison 1986)

38. CME-flare spatial relation • The asymmetric super-expansion of CME in the inner corona explains the spatial disparity in the outer corona

39. Role of Magnetic Reconnection • In 2-D flux rope model, serves as tether cutting, allowing flux rope to escape (Lin et al. 2004)

40. Role of Magnetic Reconnection • In 3-D flux rope model, serves as poloidal flux injection, increasing self-Lorentz force (“hoop” force, and gradient force), and expulsing the flux. (Note, Chen & Krall model flux injection from sub-photosphere). Chen & Krall 2003

41. Role of Magnetic Reconnection • In break-out simulation • Breakout reconnection at the top removes the overlying field • Flare reconnection underneath forms the closed flux rope (Lynch et al. 2004)

42. A Conceptual Process Phase of Energy Building-Up And closing to critical point of instability Days, weeks CME Initiation Phase Tens of minutes, Hours Strengthening current sheet Driving magnetic inflow minutes, Tens of minutes CME Main Acceleration Flare-producing magnetic reconnection days to affect the Earth CME Propagation Phase

43. Conclusion & Discussion • Broad and continuous distribution of CME acceleration • A scaling law of CME acceleration: inverse linear correlation between acceleration and magntiude • CME initiation is due to catastrophic loss of equilibrium; possible start of breakout reconnection • CME fast acceleration is due to the flare-related magnetic reconnection • What triggers the initiation? Accumulation of helicity? (Zhang Mei et al. 2006) • Why most flares are confined?