# Presentation: 520270

## Solar origin of SEP events and dynamical behaviour of the coronaMonique Pick, Dalmiro Maia, and S. Edward HawkinsLESIA, Observatoire de Paris, Meudon, FranceObservatoire de Porto, Université de Porto, PortugalApplied Physics Laboratory, John Hopkins University, Laurel, USA

- STEREO, March 2002, Paris

- 	We  review what we  learnt on the origin of energetic electron events from joint observations made with ACE, WIND, ULYSSES (ULS), imaging instruments on SOHO, radio spectrographs and the Nançay Radioheliograpgh (NRH).  ULS and ACE provided for a very few events stereoscopic observations and showed the effects of particle propagation. The main limitations of these studies   were the low cadence of the imaging instruments on SOHO and the lack of stereoscopic observations.

**	**_**The September-October 1999 period (Period of rather quiet activity. No significant solar X-ray flare)**_
- _ _
- 	Type III storms detected in the high corona and in the IP medium are long lived features associated with type I storms produced in the corona at metric wavelengths (Bougeret et al., 1994).  Noise storms (NS)  are due to electrons accelerated quasi continuously and are commonly observed by  the Nançay Radioheliograph (NRH).
- 	During this period, ULS was magnetically connected to the solar disk visible on Earth. ULS and ACE  were not located on the same IMF line. Not all the anisotropic events were observed by the two spacecrafts. This is illustrated for the 5-9 September period. The origin of a persistent anisotropy seen by ULS (and not by ACE) is associated in space and time with coronal bursty activity detected by the NRH. The radio source is located at the foot of the IMF line connected to ULS.
- 	Moreover, during the same period,  the two spacecrafts ULS and ACE detected a long duration event characterized by comparable isotropic electron intensities. This is consistent with the concept of a reservoir of seed population (Roelof et al., 92) associated at the sun with the source of a noise storm lasting several days.

**	**_**November 28 1997, series of highly-collimated electron-events**_
- 	A close association is found between three successive energetic electron events, three interplanetary type III bursts packets, and three packets of metric type III bursts. For each of these three  events, a first group of short bursts lasting from one to two minutes is followed by a second group 4-5 minutes later.  The source on the sun is located at a longitude consistent with the foot of the IMF line connected with the electron events.

**	**_**Events  associated with large scale restructuring of the magnetic field. The  July 14, 2000 flare/CME event**_

**	**_**Event associated with a flare located behind the limb. The April 20 1998 event**_
- 	Strong intensity of radio sources can mask presence of other weaker sources. For CMEs associated with flares located behind the solar limb, the strongest emitting sources will be occulted. This was the case for the April 20, 1998 event. For this event signature of the CME driven shock was detected. In addition, for the first time, the **CME expanding loops was imaged directly at radio wavelengths by non thermal synchrotron emission from electrons with energies of  ~O.5-5 MeV.** Origin of these energetic electrons is unknown: shocks or reconnection in the low corona?
- 	These radio CME events could also explain why  some electron events are released many minutes later than the flare or type III burst onset.

## Joint ULS and ACE observations of electronsSeptember 05 (248) to 09 (252)

*Left  * Spin-averaged intensities  (38-315 keV). *Right *Eight sectors (53 keV)
**ACE and ULS: Wide radial and latitudinal separation.**
**Vertical lines : Period of anisotropy seen by ULS, only.**
**Similar overall shape and intensities**** ****seen by ULS and ACE,**
**reservoir of seed particles.**

- ACE/EPAM

- ULS/HI-SCALE
-  B connection
-  **65°S-35°W**
**    ****4.6 AU**

**Source  at 15° N, 30° W**: persistent noise storm enhancement
-  which began at ~10:00 UT lasting beyond 15:30 UT.
-   **Association with the slow increase seen by ACE.**
-  **Source at 40-60° S:**  bursty event which began at ~14:00 UT
-  correlated with   IP type III (WAVES);
-  **Time association with ULS anisotropy period** (transit ~4 hour);
-  ACE was not well connected.
** ****Reservoir : persistent noise storm source (15°N,30°W)**
* **M. Pick, D. Maia, S.E. Hawkins, III Space Science Reviews, 1-4, 2001. *

**      ****NRH**
** ****3 frequencies**

**Foot points**
**(A)**** ACE**
**(U)**** ULS**

## Energetic  electron beam events November 28 1997

**WIND/WAVES**

**NRH**
**E-W plot**

**Three similar radio events located on the western limb. **
**Each event includes two successive type III groups separated**
**by ****4 or 5 minutes**
*D. Maia, M. Pick, S. E. Hawkins, S. Krucker, The Astrophys., 500, 1058, 2001*

## .ACE

_**Right**_** Onset time versus inverse velocity**
- Dashed lines correspond to a release at the time of the two
- successive type III burst groups (PAD=0). I1 is a weak event.
- I2: release at the first solar injection. **I3 incompatible with one **
**single injection.**

- .**ACE**
**° WIND**

**LASCO C1 (FeX) Coronal evolution**
**at the vicinity of the release site.**
**Opening of the B field occurs after**
**the second event I2.**

##  The July 14 2000 Halo CME event

*D. Maia, M. Pick, S. E Hawkins III,V.V. Formichev, and K. Jiricka, Solar Phys.,*
* **issue 1/2, 204, 197-212 2001.*

**This event is recurrent: After the main phase at 10: 00 UT ****(M1),**
** ****two other strong bursts ****(M2 and M3) ****are detected.**
**Two shocks associated with M1 and M3**

**WIND**

**NRH**

**M1**

**M2**

**M3**

**C1**

**M1** Radio sources spread over
- a large angular extend in  15 min.
- Moving sources N-W (V>1500 km/sec)

**M1**** **Accelerated electrons illuminate
- outward moving features launched
-  a few tens minutes after the CME onset

**M2** and **M3** are not detectable by LASCO

**M2**

**M3**

**C1**

**ACE/EPAM energetic electrons**

**~40-300 keV electrons**
**4 energy channels, PAD**
- SW 600 km/s, foot 40 W
- Spiral 1.07 AU
- Transit time 24 min
- Onset ~1040 UT
**Mapping back** **1024 UT**
- (8 min substract)
*Time indicated in the figure*
*for flare and M1 not corrected *
*for transit.*

_**Anisotropy**_**: coincides in time with radio sources **_**seen in the western**_** hemisphere. **_**Strong**_** modification observed at a longitude consistent with B foot point.**

**Anisotropy persists during many**
**hours.** ** Global and recurrent**
**coronal activity responsible for**
**populating the IP medium with**
**energetic electrons during many**
**hours.**

- M1

-  M2

- M3

**The April 20 1998 CME**

**Plasma front  (****PF****) detected in radio,**
** ****coincides with the CME leading edge**
*D. Maia, M. Pick, A. Vourlidas and R. Howard*
*The Astrophys. J., 528, L49-51*

**PF**

**RL**

**Radio CME: emitting loops (****RL****)**

## The April 20 1998 CMEDirect imaging at radio wavelengths

**The loops are illuminated by energetic electrons after ~10:06 UT**
**Gyrosynchrotron radiation ****0.5-5 MeV  electrons**
**B 0.1-few gauss  **
**Energy for electrons >100 keV  >4 10****29 ****ergs**
*	**T. S. Bastian, M. Pick, A. Kerdraon, D. Maia and A. Vourlidas, the Astrophys. J., 558, L65-69, 2001. *