Observations of energetic particles with EPAC on Ulysses in polar latitudes of the heliosphere

Science. 1995 May 19;268(5213):1013-6. doi: 10.1126/science.7754379.

Abstract

Measurements with the Energetic Particle Composition instrument (EPAC) aboard Ulysses show particles from near the ecliptic that were apparently accelerated by shocks associated with a corotating interaction region. The particles were detected together with the shocks and even when shocks no longer arrived at Ulysses up to -65 degrees of heliographic latitude but not beyond. Particles could have reached these latitudes along magnetic fields; such connections to the outer lower latitude heliosphere evidently do not exist above that latitude. The accelerated streams have composition similar to solar wind abundances, no dispersion, and a net inward anisotropy. The underlying composition between the recurrent stream is similar to the anomalous component of cosmic rays. The channel sensitive to high-energy protons (> 230 megaelectron volts) shows a 26-day variation of the flux superimposed on the heliospheric modulation of galactic ions.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acceleration
  • Extraterrestrial Environment*
  • Ions
  • Rotation
  • Solar System*
  • Spacecraft

Substances

  • Ions