Enhanced solar wind ³He2+associated with coronal mass ejections

Using data from the MASS high-resolution solar wind spectrometer on the WIND spacecraft, six enhanced ³He2+/4He2+ periods were identified from January 1995 to May 1998. The ratios observed in these events are four to ten times higher than previously reported average solar wind values. All enhanced ³He2+ periods were associated with the passage of CME-ejecta. The observed time periods were either within but towards the end of the CME-associated magnetic clouds or trailing the magnetic cloud by about 24 hours. All the enhanced ³He2+ periods have a mixture of low (cold) iron charge states along with high (hot) oxygen charge states. The unusual charge state composition of these enhanced ³He2+ events suggests the plasma came from a relatively cold and dense solar region, or from a rapidly expanding plasma parcel in the corona. We suggest that the enhanced ³He2+ plasma originated from the prominence core embedded within the CME.