Observational Properties of Coronal Mass Ejections
AIR FORCE RESEARCH LAB HANSCOM AFB MA SPACE VEHICLES DIRECTORATE
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Coronal mass ejections CMEs have been known and observed for over 30 years. The total number of observed CMEs is now approaching 10,000, most of them detected with the LASCO coronagraph on the SOHO spacecraft. We review statistical work on CME widths, latitudes, accelerations, speeds, masses, and rates of occurrence. Solar-cycle variations of these parameters are presented. Recent work has focused on CME internal properties and compositions and on CME dynamics, particularly at low 3 solar radii altitudes. The challenges to understand the magnetic topology of narrow 20 deg width CMEs, to determine the relationship of coronal holes to CMEs, and to observe magnetic reconnection that effects magnetic disconnections of CMEs from the Sun are discussed.