Variable abundance of energetic HE+ in CME related SEP events
Abstract
We have investigated several coronal mass ejections (CME) related solar energetic particle (SEP) events with unusually high abundance of He+ in the energetic particle population. There were observed between 1998 and 1999 with SEPICA on ACE and CELIAS/STOF on board SOHO. Whereas usually the abundance of He+ is below a few percent, at these times the He+ /He2+ ratio can be close to one. Possible sources for He+ are interstellar pickup ions or cold solar ejecta in CMEs. The abundance of He+ is expected to vary depending on where the major acceleration occurs, i.e. close to the sun or mainly locally close to the observer.
- Publication:
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International Cosmic Ray Conference
- Pub Date:
- August 2001
- Bibcode:
- 2001ICRC....8.3439K