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CME Interactions and Particle Acceleration
N. Gopalswamy (NASA/GSFC)
2003 February 11 Elmau CME workshop, Group-C Presentation
(B. Klecker’s Group)
In this talk…
• Broadband radio signatures due to successive CMEs (electrons)
• SEP intensity and preceding wide CMEsMore details: ApJ, 548, L91, 2001 ApJ, 572, L103, 2002 GRL 29(8), 106-1, 2002 SW10 Proceedings, 2002 GRL 2003 in press
Interacting CMEs
• Distinct radio signatures: electron acceleration
- Broadband enhancement following type II (ApJ, 548, L91, 2001)
- Radio enhancement with nothing before interaction
- Deviation from normal type II spectrum
• Implications to SEPs:
- Particles need to escape from region of interaction
- Magnetic connectivity to Earth
- SEP production and modification of acceleration
20010120 CMEs
• Two fast CMEs from the same region (AR 9313), two hours apart
• Both driving shocks
• Intense radio emission following the second
• The second CME “sees” a different corona, viz, the first CME
EIT 195 movie showing the source of the two fast CMEs
CME Interaction & SEPs: StatisticsProperty Major (>10pfu) Minor (1-10 pfu)
Total # 43 39
Avg Speed km/s 1393 927
Width >100 deg 98% (41/42) 87% (34/39)
CME Interaction 83% (35/42) 87% (34/39)
All Interactions 93% (39/42) 97% (38/39)
Assoc.w/DH II 95% (40/42) 56% (22/39)
Onset time Diff 6.9 hrs 7.1 hrs
Intersec. Height 21 Ro 21 Ro
Avg PA overlap 50 deg 52 deg
Gopalswamy et al., 2002 ApJ, 573, L103
Inverse Study: Fast &Wide CMEs • 52 fast (> 900km/s) & Wide (> 60deg) frontside,
western hemispheric CMEs. Look for SEP events.
No SEP SEP
No Interaction 4 2 (7)
Interaction 6 40 (35)
CME Interaction discriminates SEP-poor from SEP-rich
Marginal overlap ~10 deg
Including streamer interaction
Minor
Preconditioning
• SEP intensity (I) is correlated with CME velocity (V): I varies over 4 orders of magnitude, while V is in the range 500-2500 km/s [Kahler, 2001]
• Kahler considered ambient level of SEP intensity as one of the factors responsible for the scatter
• We consider preceding wide events – consistent with Kahler’s result but the effects are more than providing seed particles
Preconditioning: High SEP intensity results when preceded by a wide CME
S16W71 9415 17:54 830 km/s
S20W85 9415 14:06 1200 km/s
SEP Intensities: Coronal/IP environment matters?
Intensity
Level
With
Prewide
Without
Prewide
Total
High
>50 pfu
17 (65%) 9 (35%) 26
Low
< 50 pfu
3 (15%) 17 (85%) 20
Divide SEP events into high & low int. events
Look for preceding fast& wide events within a day from the same AR
There seems to be a tendency for the highintensity events to bepreceded by wide events
Preconditioning: Influence of Preceding Wide CMEs on SEP Intensity
• Out of the 46 major SEP events of this cycle- 26 were of high intensity (I > 50 pfu)- 20 were of low intensity (10 pfu < I < 50 pfu)- Look for wide (>60 deg) CMEs within a day ahead of the SEP
events. The average preceding time was found to be ~11 hrs• 17/26 (65%) high-intensity events and only 3/20 (15%) low-
intensity events were preceded by a wide event within a day- modification of the streaming limit?- Temporary quasiparallel geometry?• 37/47 (79%) events had enhanced background (Kahler 2001
found a weak correlation between SEP intensity and ambient level of SEPs)
Complexity of Solar EruptionsNat Gopalswamy, NASA GSFC, Greenbelt, MD
Topics to be discussed• CME-CME interactions• Radio Signatures (Energetic Electrons)• Solar Energetic Particles
More details: ApJ, 548, L91, 2001
ApJ, 572, L103, 2002
GRL 29(8), 106-1, 2002
SW10 Proceedings
http://cdaw.gsfc.nasa.gov/LWS/SHINE meeting Invited talk Plenary session August 19 2002 Banff