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 signifi cant 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' whic h may be associated with the CME footpoints. In particular, we show that th e dimming is due to a density decrease from million K plasma loss. We compa re the mass loss with the CME mass. The observations suggest that the inter action of adjacent coronal loops plays an important role in CME activity an d may allow us to pinpoint the source of the CME material.