Active-Region Filaments and X-ray Sigmoids
Abstract
We use Yohkoh soft X-ray telescope data and Hα full-disk observations to study the evolution of chromospheric filaments and coronal sigmoids in 6 active regions in association with coronal mass ejections (CMEs). In two cases, CMEs are directly observed by the SOHO/LASCO C2 coronagraph. In four cases, other observations (magnetic clouds, geomagnetic storms, sigmoid-arcade evolution) are used as CME indicators. Prior to eruption, each active region shows a bright coronal sigmoidal loop and underlying Hα filament. The sigmoid activates, erupts and gets replaced by a cusp, or an arcade. In contrast, the Hα filament shows no significant changes in association with sigmoid eruption and CME. We explain these observations in a framework of the classical two-ribbon flare model.
- Publication:
-
Solar Physics
- Pub Date:
- May 2002
- DOI:
- 10.1023/A:1015589802234
- Bibcode:
- 2002SoPh..207..111P
- Keywords:
-
- Flare;
- Active Region;
- Coronal Mass Ejection;
- Geomagnetic Storm;
- Magnetic Cloud