An unusual coronal mass ejection: First Solar Wind Electron, Proton, Alpha Monitor (SWEPAM) results from the Advanced Composition Explorer

D. J. McComas, S. J. Bame, P. L. Barker, D. M. Delapp, W. C. Feldman, J. T. Gosling, E. Santiago, R. M. Skoug, R. L. Tokar, P. Riley, J. L. Phillips, J. W. Griffee

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Abstract

This paper reports the first scientific results from the Solar Wind Electron Proton Alpha Monitor (SWEPAM) instrument on board the Advanced Composition Explorer (ACE) spacecraft. We analyzed a coronal mass ejection (CME) observed in the solar wind using data from early February, 1998. This event displayed several of the common signatures of CMEs, such as counterstreaming halo electrons and depressed ion and electron temperatures, as well as some unusual features. During a portion of the CME traversal, SWEPAM measured a very large helium to proton abundance ratio. Other heavy ions, with a set of ionization states consistent with normal (1-2 x 106 K) coronal temperatures, were proportionately enhanced at this time. These observations suggest a source for at least some of the CME material, where heavy ions are initially concentrated relative to hydrogen and then accelerated up into the solar wind, independent of their mass and first ionization potential.

Original languageEnglish (US)
Pages (from-to)4289-4292
Number of pages4
JournalGeophysical Research Letters
Volume25
Issue number23
DOIs
StatePublished - Dec 1 1999

All Science Journal Classification (ASJC) codes

  • Geophysics
  • Earth and Planetary Sciences(all)

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    McComas, D. J., Bame, S. J., Barker, P. L., Delapp, D. M., Feldman, W. C., Gosling, J. T., Santiago, E., Skoug, R. M., Tokar, R. L., Riley, P., Phillips, J. L., & Griffee, J. W. (1999). An unusual coronal mass ejection: First Solar Wind Electron, Proton, Alpha Monitor (SWEPAM) results from the Advanced Composition Explorer. Geophysical Research Letters, 25(23), 4289-4292. https://doi.org/10.1029/1998GL900174