1. August 2006 IAU Assembly Halo CMEs and Configuration of Magnetic Field Yang Liu – Stanford University yliu@solar.stanford.edu

2. August 2006IAU Assembly Introduction This is a statistical work following Liu & Hayashi (2006) who analyzed the fast halo CMEs in October-November 2003. In that work, we found that those fast halo CMEs were associated with special configurations of magnetic field. This is a statistical work following Liu & Hayashi (2006) who analyzed the fast halo CMEs in October-November 2003. In that work, we found that those fast halo CMEs were associated with special configurations of magnetic field.

3. August 2006IAU Assembly Instroduction (cont’)

4. August 2006IAU Assembly Introduction (cont’) 3D MHD simulation. 3D MHD simulation.

5. August 2006IAU Assembly Introduction (cont’) We argue that type 2 & 3 magnetic configurations work as an additional factor to ensure a high speed for the 2003 October-November fast halo CMEs when they propagate into the heliosphere, while the related flares’ characteristics may already define the CMEs’ speeds in the first place. We argue that type 2 & 3 magnetic configurations work as an additional factor to ensure a high speed for the 2003 October-November fast halo CMEs when they propagate into the heliosphere, while the related flares’ characteristics may already define the CMEs’ speeds in the first place.

6. August 2006IAU Assembly Purpose of this work Purpose: to examine whether this conclusion is held generally. Purpose: to examine whether this conclusion is held generally. Assumption: statistically, the halo CMEs with those three type configurations should have a similar speed distribution in the initial phase. Assumption: statistically, the halo CMEs with those three type configurations should have a similar speed distribution in the initial phase. Methodology: compare speed distributions of those three type CMEs. Methodology: compare speed distributions of those three type CMEs.

7. August 2006IAU Assembly Data We looked for the halo CMEs from the CMEs list of Gopalswamy’s group. 104 halo CMEs in the time interval from 2000 to 2004 were chosen. The solar sources were identified by that group. We looked for the halo CMEs from the CMEs list of Gopalswamy’s group. 104 halo CMEs in the time interval from 2000 to 2004 were chosen. The solar sources were identified by that group. Type 1 Type 2 Type 3 number414815 percentage39%46%15%

8. August 2006IAU Assembly

9. August 2006IAU Assembly Distribution of CMEs versus flare class.

10. August 2006IAU Assembly Weak correlation was found between the speed of type 3 CMEs and the peak X- ray flux of the associated flares.

11. August 2006IAU Assembly Conclusions Types 2 & 3 CMEs appear to be faster than type 1. Types 2 & 3 CMEs appear to be faster than type 1. It is shown that the background magnetic configuration associated with halo CMEs does play a role in determining the speeds of the CMEs. It is shown that the background magnetic configuration associated with halo CMEs does play a role in determining the speeds of the CMEs. A weak correlation was found between the speed of type 3 CMEs and the peak of X-ray flux of the associated flares. A weak correlation was found between the speed of type 3 CMEs and the peak of X-ray flux of the associated flares.