Comparison of CME characteristics for SEP and non-SEP related events Original Research Article

A comparison is made between flare-associated CMEs that produce SEPs and those that do not to determine what role CME velocity, flare duration, and CME-flare time delays play in SEP production. 62 SEP events were selected from a list compiled by NOAA. The non-SEP list was made up of CMEs chosen to mimic the SEP-related CMEs as closely as possible in terms of solar cycle, flare association, and appearance and contained 50 events. For each CME, multiple features, such as leading edges, streamers, or bright points, were identified and tracked to yield time–height curves that intersect at a low height. The intersection time of these tracks is taken to be the “launch time” of the CME. The leading edge speed of the SEP events (1255 km/s) is larger than non-SEP events (926 km/s), even when comparing events with similar flare associations. Flare durations were not significantly different between the two groups. The time delay between CME onset and flare start time is similar for both categories.