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W.M. Neupert (NOAA/SEC)
Knowledge of the acceleration of coronal mass ejections (CMEs) in the low corona is vital in properly relating such eruptions to prior activity in the chromosphere and low corona and thereby identifying the processes that initiate these events. Observations made by the EUV Imaging Telescope (EIT) on the Solar Heliospheric Observatory (SOHO) have been used to track off-limb transients, both coronal plasmas and erupting filaments, from their pre-event locations, through their periods of maximum acceleration, and into the fields of view of the white light coronagraphs (LASCO), also on board SOHO. In all instances studied (limited by the cadence of EIT observations), CME acceleration as observed in the EIT images was preceded by filament activity and in one instance, of an erupting quiescent filament observed against the solar disk, by the appearance of a new magnetic region to one side of the filament. This filament activity was followed by an initially slow increase in height of one or more faint coronal loops (observable only above the solar limb) that then accelerated at rates as high as 0.5 km/s/s between 100 Mm and 750 Mm above the solar surface. For CMEs that originated on the visible side of the Sun, this acceleration coincided with a rapid rise in the soft X-ray flux as measured by GOES. No transient coronal changes that might suggest reconnection in the higher corona were observed in the LASCO coronagraph fields of view. These results imply that the CME is initiated by localized magnetic activity in the chromosphere or at the very base of the corona. This work was supported by NASA Contract NAS5-00220 with L-3Comm/Analytics.
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Bulletin of the American Astronomical Society, 34
© 2002. The American Astronomical Soceity.