Flare-associated coronal disturbances observed with the Norikura Green-Line Imaging System. I. A coronal mass ejection onset

We present the first detection of an onset of a coronal mass ejection (CME) in the coronal green-line emission (Fe XIV lambda5303, 2 MK) by the two-dimensional Doppler coronagraph NOGIS (Norikura Green-Line Imaging System) at the Norikura Solar Observatory, National Astronomical Observatory of Japan. On 2003 June 1-2, NOGIS continuously observed the birthplace of a CME that originated in a complex of two neighboring magnetic flux systems across the solar equator: a flare-productive NOAA Active Region 10365, and a bundle of face-on coronal loops overlaying a quiescent filament. An early precursor of the event was a density enhancement of a 2 MK plasma in between the two flux systems. Following a filament eruption from NOAA AR 10365 that was observed by the Transition Region and Coronal Explorer (TRACE) in the 195 Angstrom passband (1.6 MK), NOGIS observed a blueshifted bubble and a redshifted wave that almost simultaneously expanded from the boundary of NOAA AR 10365 and the overlying dense region. The redshifted wave propagated toward the face-on loop system and triggered a damping oscillation in Doppler shifts among the adjacent loops within the system. The blueshifted bubble propagated both inward and upward. The inward motion triggered an M6.5 flare in AR 10365, while the upward motion evolved into a partial halo CME that had an angular extent covering the latitudinal range of the two flux systems. Differing from typical CME disturbances that evolve within a single flux system with a bipolar arcade on its center, our event proceeded via interaction, which was a presumably magnetic reconnection between separatrices of the two flux systems. These observational properties may suggest the existence of "CME corridors'' in multiple complex flux systems, from which huge CMEs can be launched.