Corona Mass Ejection (CME) 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) 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.

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

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

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

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.

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

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

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

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

CME Morphology

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

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.

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

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

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

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.

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

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

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

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

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

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

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

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.

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

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)

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