A spectroscopic study of coronal dimming associated with a coronal mass ejection

Extreme ultraviolet spectroscopic observations of one coronal mass ejection event are used to examine the onset phase of the eruption. We find significant dimming of million K plasmas in the low corona under the ascending CME, the activation of an adjacent prominence and 2 million K ‘hot spots’ which may be associated with the CME footpoints. In particular, we show that the dimming is due to a density decrease from million K plasma loss. We compare the mass loss with the CME mass. The observations suggest that the interaction of adjacent coronal loops plays an important role in CME activity and may allow us to pinpoint the source of the CME material.