Energetic particle anisotropies and remote magnetic connection at high solar latitudes

Abstract

A very stable pattern of energetic particle events recurring with the solar rotation period dominates the Ulysses high latitude energetic particle observations during the current solar minimum. Most of these events can be associated with reverse shocks of corotating interaction regions (CIRs) but at latitudes above 50 deg there are either no shocks observable at all or the events are retarded by 2-4 days with respect to the shock passage. This has been explained either by cross-field diffusion from low latitude CIRs or by remote magnetic connection to a CIR expanding in latitude with distance. Using data from the Ulysses EPAC instrument we show that anisotropies of 0.7 MeV/N Helium ions are in favour of the remote magnetic connection theory.