Halo CMEs are classified as symmetric (S), brightness-asymmetric (BA), and outline-asymmetric (OA).
|
|
| A halo with Symmetry (S): The heliocentric distance of the CME leading edge is the roughly same at all position angles. | |
 |
 |
| A halo with Brightness Asymmetry (BA): The heliocentric distance of the CME leading edge is the roughly same, but the CME brightness is significantly different at different position angles. | |
 |
 |
| A halo with Outline Asymmetry (OA): The heliocentric distance of the CME leading edge is significantly different at different position angles. | |
| Halo CMEs are also classified as Full halos (type F), Asymmetric halos (type A) and Partial halos (type P). [see Gopalswamy et al., 2003 for details]. Type F corresponds to (S) and (BA). Type A corresponds to OA. Type P are CMEs with with between 120 and 359 degrees. |
|