TWO-PLASMA MODEL FOR LOW CHARGE STATE INTERPLANETARY CORONAL MASS EJECTION OBSERVATIONS

Abstract

Recent ACE/SWICS observations have revealed that ~5% of all in situ observed interplanetary coronal mass ejections include time periods with very low charge state ions found to be associated with prominence eruptions. It was also shown that these low charge state ions are often observed concurrently with very high charge state ions. But, the physical process leading to these mixed charge states is not known and could be caused by either the mixing of plasmas of different temperatures or by non-local freeze-in effects as discussed by Gruesbeck. We provide a detailed and multi-stage analysis that excludes this latter option. We therefore conclude that time periods of very low charge states are the heliospheric remnants of plasmas born in prominences. We further conclude that the contemporaneously observed low and very high charge states are an indication of mixing of plasmas of different temperatures along magnetic field lines, suggesting that silicon and iron are depleted over carbon and oxygen in the cold, prominence-associated plasma. This represents the first experimental determination of elemental composition of prominence-associated plasma.