Eruption of a flux rope on the disk of the sun: Evidence for the coronal mass ejection trigger?

The first evidence of acceleration of a flux rope from the disk of the Sun using the Coronal Diagnostic Spectrometer (CDS) on the Solar and Heliospher ic Observatory (SOHO) is presented. A distinct blueshifted emission compone nt (-480 km s(-1)) was observed by the EUV spectrometer on SOHO at the star t of the impulsive phase of an X2.3 flare. There is a halo coronal mass eje ction associated with this event. Based on a sequence of velocity measureme nts, we determine the acceleration of the erupting material. These results are supported by simultaneous EUV imaging data from the Transition Region a nd Coronal Explorer spacecraft, which shows the projected motion of the flu x rope. The CDS spectra reveal an initial rapid acceleration phase (3.5 km s(-2)), followed by a transition to a more gradual acceleration (0.68 km s( -2)). This may indicate energy input via explosive reconnection.