Simultaneous high Fe charge state measurements by solar energetic particle and solar wind instruments

Abstract

During the May 2–3, 1998 CME event, iron charge state distributions were observed on the ACE spacecraft simultaneously in both solar energetic particles and the solar wind. Surprisingly, common signatures were found, even though the energy of these two particle populations differ by about two orders of magnitude. At the beginning of the event a substantial shift towards higher charge states (Q ≥ 14)(Q⩾14) was detected for Fe nearly simultaneously in solar energetic particles by SEPICA, and in the solar wind by SWICS. The onset in the solar wind was somewhat more gradual, beginning approximately two hours before the rather sudden onset in the solar energetic particles. The high iron charge states coincided approximately with the magnetic cloud associated with the CME. Later, during the cloud passage, periods of high and unusually low, iron ionization states were observed in the solar wind. Just after the passage of the cloud, iron with high charge states again appeared in both energetic particles and the solar wind. Transport and acceleration scenarios will be discussed as possible explanations of this unusual event. © 2000 American Institute of Physics.