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Corona Mass Ejection (CME) And Solar Energetic Particle Events

CSI 769-001/PHYS 590-001 Solar Atmosphere Fall 2004 Lecture 13 Dec. 01, 2004. Corona Mass Ejection (CME) And Solar Energetic Particle Events. A Typical Coronagraph Image: Streamers. Streamer (cont’d).

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Corona Mass Ejection (CME) And Solar Energetic Particle Events

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  1. CSI 769-001/PHYS 590-001 Solar Atmosphere Fall 2004 Lecture 13 Dec. 01, 2004 Corona Mass Ejection (CME) And Solar Energetic Particle Events

  2. A Typical Coronagraph Image: Streamers

  3. Streamer (cont’d) • A streamer is a stable large-scale structure in the white-light corona. • It has an appearance of extending away from the Sun along the radial direction • It is often associated with active regions and filaments/filament channels underneath. • It overlies the magnetic inversion line in the solar photospheric magnetic fields. • When a CME occurs underneath a streamer, the associated streamer will be blown away • When a CME occurs nearby a streamer, the streamer may be disturbed, but not necessarily disrupted.

  4. CME: a transient phenomenon A LASCO C2 movie, showing multiple CMEs

  5. Measuring a CME H (height, Rs) PA (position angle) AW (angular width) M (mass)

  6. Measuring a CME (cont’d) A typical measurement: # HEIGHT DATE TIME ANGLE TEL FC COL ROW 2.77 2003/01/03 11:30:05 318.7 C2 1 329.0 336.0 3.10 2003/01/03 11:54:07 318.1 C2 1 339.0 345.0 3.35 2003/01/03 12:06:05 318.5 C2 1 345.0 353.0 3.78 2003/01/03 12:30:05 319.2 C2 1 355.0 367.0 4.08 2003/01/03 12:54:05 319.7 C2 1 362.0 377.0 5.40 2003/01/03 13:31:44 316.8 C2 1 405.0 410.0 6.16 2003/01/03 13:42:05 314.5 C3 1 297.0 304.0 6.41 2003/01/03 13:54:05 316.0 C2 1 436.0 437.0 6.92 2003/01/03 14:06:05 316.7 C2 1 448.0 454.0 7.71 2003/01/03 14:18:05 316.4 C3 1 305.0 315.0 9.10 2003/01/03 14:42:30 317.7 C3 1 312.0 325.0 10.64 2003/01/03 15:18:05 316.8 C3 1 322.0 334.0 12.28 2003/01/03 15:42:05 318.1 C3 1 330.0 346.0 14.16 2003/01/03 16:18:05 318.0 C3 1 341.0 358.0 15.70 2003/01/03 16:42:05 317.4 C3 1 351.0 367.0 18.34 2003/01/03 17:18:05 318.5 C3 1 364.0 386.0

  7. CME Property: velocity • Velocity is derived from a series of CME H-T (height-time) measurement • A CME usually has a near-constant speed in the outer corona (e.g, > 2.0 Rs in C2/C3 field) • Note: such measured velocity is the projected velocity on the plane of the sky; it is not the real velocity in the 3-D space.

  8. CME Property: velocity • CME velocity ranges from • 50 km/s to 3000 km/s • Average velocity: 400 km/s • Peak velocity: 300 km/s • Median velocity: 350 km/s 6300 LASCO CMEs from 1996 to 2002

  9. CME Property: size AW = 80 degree AW = 360 degree, halo CME

  10. CME Property: size • Broad distribution of CME apparent angular width • Average width 50 degree • A number of halo CMEs (AW=360 degree), or partial halo CMEs (AW > 120 degree) • Halo CMEs are those likely impacting the Earth orbit

  11. CME Property: mass • CME mass distribution from 1013 to 1016 gram • Average CME mass about 1015 gram Based on 2449 LASCO CMEs From 1996 to 2000

  12. CME Morphology

  13. CME morphology (cont’d) • Three part CME structure • A bright frontal loop (or leading edge) • Pile-up of surrounding plasma in the front • A dark cavity (surrounded by the frontal loop) • possibly expanding flux rope or filament channel • A bright core (within the cavity) • Composed of densely filament remnant material

  14. CMEs and Other Solar Activities • CMEs are often associated with flares; extremely fast CMEs (2000 km/s) are mostly associated with major flares (X class). • CMEs are also associated with filament eruptions. • CME are often associated with coronal dimmings • However, there are always exceptions in each type of association.

  15. CMEs and Other Solar Activities (cont’d) • Exp. A CME associated with a flare

  16. CMEs and Other Solar Activities (cont’d) • Exp. A CME associated with a filament EIT movie of 2000/02/27 showing filament eruption C2 movie of 2000/02/27 CME

  17. CMEs and Other Solar Activities (cont’d) • Exp. A CME associated with a (EIT) coronal dimming Coronal dimming, often seen in EIT 195 Å images (1.5 MK), is caused by mass depletion following CME eruption

  18. kinematic Evolution of a CME • A CME is strongly accelerated in the inner corona (<2 Rs); unfortunately, inner corona observations have been very poor. • A CME maintains a more or less constant speed when it travels in the outer corona (>2 Rs); it interacts with background solar wind in the interplanetary space.

  19. Geo-effective CMEs: halo CMEs • Whether a CME is able to intercept the Earth depends on its propagation direction in the heliosphere. • A halo CME (360 degree of angular width) is likely to have a component moving along the Sun-Earth connection line • A halo is a projection effect; it happens when a CME is initiated close to the disk center and thus moves along the Sun-Earth connection line. • Therefore, a halo CME is possibly geo-effective. 2000/07/14 C2 EIT

  20. CME models • A model shall include many observational elements • CME • front • cavity • core • Flare • X-ray loop • EUV loop arcade • Hα flare ribbon • Magnetic reconnection • Current sheet • Reconnection inflow • Some Others • filament eruption • coronal dimming • timing relation • Energetic relation

  21. CME models (cont’d) Lin’s CME eruption model: MHD analytic solution

  22. CME models (cont’d) Antiocs’s CME eruption model: MHD numeric solution

  23. Solar Energetic Particle (SEP) Events SEP hit LASCO CCD, causing degrading of images.

  24. Solar Energetic Particle (SEP) Events Proton flux measured in-situ (at Geo-stationary orbit) by GOES satellite SEP onset: 2001/11/04 17:00 UT, proton flux increases by 5 order of magnitude

  25. Solar Energetic Particle (SEP) Events Flare onset time: 2001/11/04 16:03 UT CME onset time: 2001/11/04 16:35 UT SEP onset time: 2001/11/04 17:00 UT Time delay from the Sun to the Earth is in the order of ten minute SEP travels at near-relativistic speed

  26. SEP Events • SEP events are increases of energy particles. • They are observed in the near earth space environment, outside the magnetosphere and in the earth polar caps • They are also observed everywhere in the interplanetary medium.

  27. SEP Events Impulsive Event Gradual Event Observed by ACE/EPAM and IMP-8/CPME

  28. SEP Events • Two kinds: gradual and impulsive events • Impulsive events • Impulsive short-duration events of hours • Relatively small proton flux • Mainly associated with flares, but not CMEs • From a narrow helio-longitude (~30 degree in western hemisphere), where magnetic field lines are well connected with the Earth • Gradual events • Have a duration of several days • Large proton flux • Associated with CMEs. • From a broad range of helio-longitudes (180 degree)

  29. Particle Acceleration Mechanisms • SEP events are caused by flares and/or CMEs • Flare mechanisms • SEP caused by magnetic reconnection • Wave-particle resonance in flaring region • Direct electric field induced by reconnection • Source of impulsive SEP events • CME mechanism • SEP caused by CME-driven shock • Shock forms at the front if CME speed exceeds local Alfven speed • Shock waves can accelerate particles through by bouncing particles back and forth across the shock front gaining speed with each bounce • Source of gradual SEP events

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