Persistent energetic ^3He in the inner heliosphere
Using data from the Solar Isotope Spectrometer on NASA's Advanced Composition Explorer spacecraft we have examined the time and energy dependence of the quiet-time 5–15 MeV/nuc He intensity from 1998 through 2006 in order to establish the origin of these particles. We find a mixed population, with He from impulsive solar energetic particle events dominating at the lower end of this energy interval and galactic secondary He becoming significant at the high end.
Additional InformationCopyright Universidad Nacional Autónoma de México We thank Glenn Mason for providing the ULEIS data shown in Figs. 1 and 2. This work was supported by NASA at Caltech (under grant NAG5-12929), JPL, and GSFC. This work benefited from discussions at international team meetings hosted by the International Space Science Institute (ISSI) in 2006 and 2007.
Published - 2008-09.pdf