Solar wind observations with the ion composition instrument aboard the ISEE-3/ICE spacecraft |
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| Authors: | K W Ogilvie M A Coplan P Bochsler J Geiss |
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| Institution: | (1) NASA/Goddard Space Flight Center, Laboratory for Extraterrestrial Physics, Code 692, 20771 Greenbelt, MD, U.S.A.;(2) Institute for Physical Science and Technology, University of Maryland, 20742 College Park, MD, U.S.A.;(3) Physikalishes Institut, University of Bern, Bern, Switzerland |
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| Abstract: | In this paper we use the observations of solar wind helium ions made by the Ion Composition Instrument (ICI) on the ISEE-3/ICE spacecraft to study the variation of helium abundance in the solar wind and to arrive at an average value of that quantity for the period August 1978 to December 1982. The abundance varies in a similar way to that observed in the previous solar cycle, but more detailed dependence on velocity and solar cycle epoch is observed. The long-term average helium abundance is used in conjunction with long term abundances of 3He, O, Ne, Si, and Fe, measured with respect to helium using the same instrument, to compile abundances with respect to hydrogen which can be reliably compared with solar system abundances. With the extended data set we are able to show Si and Fe to be overabundant by a factor of three with respect to solar system abundances and He underabundant by a factor of two. |
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