Relationship between EIT posteruption arcades, coronal mass ejections, the coronal neutral line, and magnetic clouds

There is observational evidence that the elongation of an Earth-directed coronal mass ejection (CME) may indicate the orientation of the underlying erupting flux rope. In this study, we compare orientations of CMEs, magnetic clouds (MCs), EIT (EUV Imaging Telescope) posteruption arcades, and the coronal neutral line (CNL). We report on good correlations between (1) the directions of the axial field in the EIT arcades and the elongations of halo CMEs, and (2) the tilt of the CNL and MC axis orientations. We found that majority of the eruptions that had EIT arcades, CMEs, and MCs similarly oriented also had the CNL co-aligned with them. On the other hand, those events that showed no agreement between orientations of the EIT arcades, CMEs, and MCs had their MCs aligned with the CNL. We speculate that the axis of the ejecta may be rotated in such a way that it is locally aligns itself with the heliospheric current sheet.