The Deflection of Coronal Mass Ejections by the Ambient Coronal Magnetic Field Configuration

Abstract

AbstractSolar coronal mass ejections (CMEs) are sometimes deflected during their propagation. This deflection may be the consequence of an interaction between the CME and the ambient coronal field, for example, a coronal hole, or the solar wind. The coronal magnetic field configuration is computed from daily synoptic maps of magnetic field from SOHO/MDI and SDO/HMI using a Potential Field Source Surface model. We analyze 30 halo‐CMEs whose deflection angle exceeds 90° by comparing the ambient magnetic field configuration and the measurement position angles of the CMEs. We find that the deflection of 87% of the CMEs (26 of 30) is consistent with the ambient magnetic field configuration, agreeing with previous studies. Of these 26, 69% are deflected toward the heliospheric current sheet, the boundary between the magnetic field polarities, and 31% toward a pseudo‐streamer, the boundary between same‐polarity magnetic field regions. This implies that the ambient coronal magnetic field configuration plays an important role in the deflection of CMEs and that the current sheet configuration is more important than a pseudo‐streamer. Of the 26 CMEs, the average and standard deviation of the minimum values of the deflection angle in three dimensions relative to an initially radial trajectory are 28° and 14°, respectively.