Observations of shock acceleration signatures by Ulysses: the 04:08:16, day147, 1991 UT shock

Abstract

We analyze the acceleration signatures of energetic ions (E>50keV) and electrons (E>30keV) observed on day 147, 1991 UT in the vicinity of the surface of a fast-mode hydromagnetic shock, using fine time resolution measurements by the HI-SCALE instrument onboard the Ulysses spacecraft. The observations present strong evidence for the acceleration of energetic particles trapped within magnetic structures on the surface of the fast-mode shock. We discuss the flux-time profiles and particle distributions near the shock in the context of previous theoretical studies and models.