Model for the Mass Fractionation in the January 6, 1997, CME

Authors: Wurz, P., Bochsler, P., and Lee, M. A.
Reference: Fall AGU 1999

Abstract: For the coronal mass ejection (CME) of January 6, 1997, a strong element fractionation of the heavy ions was observed with the SOHO/CELIAS/MTOF instrument at 1 AU. During the passage of the CME plasma and the passage of the erupted filament, which followed the CME, a mass-dependent element fractionation was found, with a monotonic increase toward heavier elements. Si/O and Fe/O ratios around 0.5 were observed. With a theoretical model we can reproduce the observed element fractionation. The model assumes hot coronal loops as the precursor of the CME. Diffusion perpendicular to the magnetic field lines results in the preferential loss of lighter ions in the loop, leading to mass fractionation. To quantitatively reproduce the fractionation, the loops must have existed at least seven days before they became part of the CME plasma, a time which is commensurate with optical observations.

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Last Update: November 9,1999, James Weygand