Science, Vol 268, Issue 5213, 1010-1013
Copyright © 1995 by American Association for the Advancement of Science
Over the southern solar pole: low-energy interplanetary charged particles
LJ Lanzerotti,
TP Armstrong,
RE Gold,
CG Maclennan,
EC Roelof,
GM Simnett,
DJ Thomson,
KA Anderson,
SE Hawkins 3rd,
SM Krimigis,
and
al. et
AT&T Bell Laboratories, Murray Hill, NJ 07974, USA.
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 approximately -75 degrees 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 approximately -75 degrees on the Ulysses ascent to the pole and approximately -50 degrees 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 (approximately 2 to 5 megaelectron volts per nucleon) oxygen flux at the highest heliolatitudes was found to be approximately 10(-8) [per square centimeter per second per steradian (per kiloelectronvolt per nucleon)]; the anomalous Ne/O ratio was approximately 0.25.
