High-latitude observations of energetic ions during the first Ulysses polar pass

Abstract

We present observations of energetic ions from the Ulysses COSPIN Low Energy Telescope in the mid and high-latitude regions of the heliosphere prior to and during the first polar pass of the Ulysses spacecraft. After the encounter with Jupiter, Ulysses started on its journey out-of-the-ecliptic. Between ∼13°S and ∼29°S the spacecraft sampled the solar wind from both the streamer belt and the polar coronal hole. Here, co-rotating magnetic structures with forward and reverse shocks and containing accelerated energetic ions were observed.At latitudes greater than ∼29°S, Ulysses was completely immersed in the solar wind from the polar coronal hole. Here the co-rotating magnetic structures were weaker, and in general had only reverse shocks, but were still capable of accelerating the energetic ions, albeit with reduced intensity. The most recent results show that beyond ∼50°S, very few if any, reverse shocks are observed. However, accelerated ions from magnetic interaction regions are still observed. We report also on an intensity enhancement at ∼50°S due to the passage of a high-latitude CME.