Over the Southern Solar Pole: Low-Energy Interplanetary Charged Particles
Simnett, G. M.; Pick, M.; Anderson, K. A.; Krimigis, S. M.; Tappin, S. J.; Lanzerotti, L. J.; Armstrong, T. P.; Gold, R. E.; Lin, R. P.; Roelof, E. C.; Sarris, E. T.; Maclennan, C. G.; Hawkins, S. E., III; Thomson, D. J.
United States
Abstract
The heliosphere instrument for spectrum, composition, and anisotropy (HISCALE) recorded the fluxes of low-energy ions and electrons (>50 kiloelectron volts) when Ulysses crossed the southern solar polar region and revealed that the large-scale structure of the heliosphere to at least ~-75^circ was significantly influenced by the near-equatorial heliospheric current sheet. Electrons in particular were accelerated by the current sheet-produced and poleward-propagating interplanetary reverse shock at helioradii far from the Ulysses location. At heliolatitudes higher than ~-75^circ on the Ulysses ascent to the pole and ~-50^circ on the descent, small, less regular enhancements of the lowest energy electron fluxes were measured whose relations to the current sheet were less clear. The anomalous component of low-energy (~2 to 5 megaelectron volts per nucleon) oxygen flux at the highest heliolatitudes was found to be ~10-8 [per square centimeter per second per steradian (per kiloelectronvolt per nucleon)]; the anomalous Ne/O ratio was ~0.25.