The timing of flares associated with the two dynamical types of solar coronal mass ejections

In this Letter, we consider a sample of Transition Region and Coronal Explorer flare-associated solar coronal mass ejections (CMEs) and study the timing behavior of the flares associated with fast or slow CMEs. We find that flares associated with fast CMEs tend to happen within half an hour of the CME onsets, while the timing of flares associated with slow CMEs is only loosely related to the CME onsets. This suggests that the occurrence of flares may be integral to the early development of fast CMEs but is not crucial for slow CMEs. This observational result supports a recent qualitative theory of the initiation and expulsion mechanism of the two dynamical types of CMEs.