Geophysical Research Letters

Ion dynamics and distribution around comet Halley: Suisei observation


  • T. Mukai,

  • W. Miyake,

  • T. Terasawa,

  • M. Kitayama,

  • K. Hirao


Ion dynamics inside the cometosheath of Halley is described based on the plasma observation by Suisei. The pickup shells of water-group ions and protons of cometary origin are clearly identified. Field line draping around the comet is observed within 2 × 105 km of the Halley's nucleus, where magnetic field directions are derived from the symmetry axes of the ion-pickup shells. Flow turbulence is observed as short-term (period of ≲ 2min) fluctuations of the anisotropy direction in the outer cometosheath (2-4.5 × 105 km from the nucleus), while the flow is found to be laminar near the closest approach (1.5-2 × 105 km from the nucleus). Spatial distribution of density of water-group ions (identified up to 4 × 106 km from the nucleus) is also presented.