Filament Eruptions and Halo Coronal Mass Ejections

Abstract

This paper shows that the solar disk counterparts to a halo coronal mass ejection (CME) display an evolution of vector magnetic fields as well as dynamics in the solar atmosphere. We examine the active phenomena in NOAA Active Region 8375, the surface source region of the halo CME, on 1998 November 4, using ground-based and space-borne observations from Huairou Solar Observing Station, the Transition Region and Coronal Explorer, the Solar and Heliospheric Observatory, and Yohkoh. The vector magnetic fields in this region have the following properties: the main positive-polarity line-of-sight field of a sunspot with the transverse field component rotating counterclockwise when looking downward against the photosphere, surrounded by relatively weak negative-polarity fields; many moving magnetic features emerged from the sunspot periphery and either cancelled the opposite-polarity fields or merged with the same-polarity fields. In the observational interval, there were two filaments lying above the neutral line between the main positive sunspot field and its surrounding weak negative fields. The eruption of each filament triggered a C-class flare. This active region was inferred as the surface region of the halo CME initiation. The halo CME consisted of several components; the two main components were associated with the two eruptive filaments and flares.