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

The two CMEs are indistinguishable at

23:42 UT

830 km/s(S07E40)

1460 km/s(S07E46)

~200%

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

Two Nearby Fast Eruptions

SEP Intensities

CME 2 S15W341450 km/s

CME1 S25W671450 km/s

1

2

P

WAVES type IIs

CME1 CME2

II-1

II-2

Continued to lower frequencies as one of the most spectacular

IP type IIs

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

Type IIIs similar

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