Low energy charged particles in the high latitude heliosphere

Abstract

Low energy ion and electron measurements made over the south and north polar regions of the sun by the HI-SCALE instrument on the Ulysses spacecraft during its solar minimum polar passages are summarized. The polar flux levels were considerably reduced in comparison to fluxes in the vicinity of the heliospheric current sheet. Flux variations with a period of ~26 days were seen to nearly 80 degS but were not observed over the northern pole. Comparisons with in-ecliptic measurements made during the same time interval on the IMP-8 spacecraft suggest that the polar differences are largely spatial and not temporal. The flux of low energy (~0.8-5 MeV/nucl) anomalous oxygen was measured to be ~50% higher over the northern polar region than in the south.