On-the-disk development of the halo coronal mass ejection on 1998 May 2

A halo coronal mass ejection (CME) was observed at 15:03 UT on 1998 May 2 b y the Solar and Heliospheric Observatory Large-Angle Spectrometric Coronagr aph. The observation of the CME was preceded by a major soft X-ray flare in NOAA Active Region 8210, characterized by a delta spot magnetic configurat ion and some activity in region 8214. A large transequatorial interconnecti ng loop (TIL) seen in the soft X-rays connected AR 8210 to a faint magnetic field region in the periphery of region 8214. Smaller loop systems were al so connecting AR 8210 to other fainter bipolar magnetic structures, the int erconnecting loop (IL) east of AR 8210 being one of the most visible. We pr esent here a multiwavelength analysis of the large- and small-scale coronal structures associated with the development of the flare and of the CME, wi th emphasis placed on radio-imaging data. In the early phases of the flare, the radio emission sources traced the propagation paths of electrons along the TIL and the IL, which are accelerated in the vicinity of AR 8210. Furt hermore, jetlike flows were observed in soft X-rays and in H alpha in these directions. Significantly, the TIL and IL loop systems disappeared at leas t partially after the CME. An EUV Imaging Telescope (EIT) dimming region of similar size and shape to the soft X-ray TIL, but noticeably offset from i t, was also observed. During the "flash" phase of the flare, new radio sour ces appeared, presenting signatures of destabilization and reconnection at discrete locations of the connecting loops. We interpret these as possible signatures of the CME liftoff on the disk. An H alpha Moreton wave (blast w ave) and an "EIT wave" were also observed, originating from the flaring AR 8210. The signatures in radio, after the wave propagated high into the coro na, include type II-like emissions in the spectra. The radio images link th ese emissions to fast-moving sources, presumably formed at locations where the blast wave encounters magnetic structures. The opening of the CME magne tic field is revealed by the radio observations, which show large and expan ding moving sources overlying the later-seen EIT dimming region.