Coronal Mass Ejection - Association With Other Solar Phenomena

Association With Other Solar Phenomena

Coronal mass ejections are often associated with other forms of solar activity, most notably:

• Solar flares
• Eruptive prominence and X-ray sigmoids
• Coronal dimming (long-term brightness decrease on the solar surface)
• EIT and Moreton waves
• Coronal waves (bright fronts propagating from the location of the eruption)
• Post-eruptive arcades

The association of a CME with some of those phenomena is common but not fully understood. For example, CMEs and flares are normally closely related, but there was confusion about this point caused by the events originating beyond the limb. For such events no flare could be detected. Most weak flares do not have associated CMEs; most powerful ones do. Some CMEs occur without any flare-like manifestation, but these are the weaker and slower ones. It is now thought that CMEs and associated flares are caused by a common event (the CME peak acceleration and the flare impulsive phase generally coincide). In general, all of these events (including the CME) are thought to be the result of a large-scale restructuring of the magnetic field; the presence or absence of a CME during one of these restructures would reflect the coronal environment of the process (i.e., can the eruption be confined by overlying magnetic structure, or will it simply break through and enter the solar wind).