Acceleration of cometary plasma in the vicinity of comet Halley associated with an interplanetary magnetic field polarity change

Abstract

Based on the ion plasma and magnetic field observations of Vega−1 near its closest approach to comet Halley a self‐consistent scenario is developed according to which the observed magnetic field topology, the observed burst of ions at energies 200–600 eV, and the observed directional dependence of the flow of these ions leads to the conclusion that these burst‐particles are cometary ions which have been accelerated by the process of merging of magnetic field lines of opposite polarity.