Coronal mass ejections and long risetimes of solar energetic particle events

Abstract

We have surveyed the risetimes of all E > 15 MeV solar energetic proton (SEP) events observed on the NOAA GOES spacecraft between 1984 and 1989 and associated with well‐connected (W20‐W70) solar flares. Twelve events occurred during the times of observations by the coronagraph on the SMM spacecraft, and each event was associated with a coronal mass ejection (CME) observed above the west limb. In each of the three SEP events with the longest flux risetimes a second CME was observed before the time of peak flux. While all the initial CMEs were associated with prominent solar flares, the subsequent CMEs were not accompanied by obvious X ray or radio bursts. We interpret the long risetimes of two of the three SEP events in terms of a second SEP injection due to the second CME.