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An unusual coronal mass ejection: First solar wind electron, proton, alpha monitor (SWEPAM) Results from the Advanced Composition Explorer
Author(s) -
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.
Publication year - 1998
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/1998gl900174
Subject(s) - coronal mass ejection , solar wind , physics , proton , interplanetary medium , electron , astrophysics , ionization , solar flare , solar energetic particles , heliosphere , ion , coronal cloud , astronomy , atomic physics , plasma , interplanetary spaceflight , nuclear physics , quantum mechanics
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 (1–2×10 6 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.