Are Homologous Flare–Coronal Mass Ejection Events Triggered by Moving Magnetic Features?

Abstract

Coronal mass ejections (CMEs) often present destabilization and eruption of a global (or large-scale) magnetic structure in the solar atmosphere. Furthermore, the Earth-directed CMEs are the primary driver of the disastrous space weather. Here we report on five homologous CMEs. They initiated in the early phase of five homologous X-class flares seen in NOAA Active Region 9236 on 2000 November 24-26. The flares appeared between the main sunspot with positive magnetic field and the moat of the active region. We examined the magnetic evolution in the source active region for the first three of the five flare-CME events and found that the main magnetic changes are magnetic flux emergence in the form of moving magnetic features (MMFs) in the vicinity of the main positive magnetic field. There are three peaks in the flux (number) distribution of the emerging MMFs. If each peak corresponds to an X-class flare and associated halo CME, there is a time lag of 10 hr between flux emergence and flaring. The flux appearing in the form of MMFs is 1.1 × 10 22 Mx, with a net flux of -2.1 × 10 21 Mx. Around the main spot region, about 9.1 × 10 21 Mx of flux disappeared in the 2 day interval. This is indicative that the repeated flare-CME activities are triggered by the continuous emergence of MMFs.