Change in photospheric magnetic flux during coronal mass ejections

Abstract

We report on the variations of photospheric magnetic flux during coronal mass ejections (CMEs). Using magneograms from the SOHO/MDI instrument, we have computed the magnetic flux of 7 active regions and one disappearing filament region associated with CMEs. When we plotted the flux versus time over a period of few days before, during and after the CME event, we found changes in the mean magnetic flux per pixel (∼4 arcsec²), ranging from ∼0.4 to ∼3.1 × 10¹⁷ Mx, in structures of size smaller than the active region. Flare onsets and the filament disappearance clearly occurred during periods of significant variations in the measured magnetic flux.