The Near-Nuclear Coma of Comet Halley in March 1986

The cameras carried onboard the flyby missions to comet P/Halley in 1986 imaged the near nuclear jet activity from several spatial directions. The observed, very structured near nuclear dust jets were considered at that time as the result of dust emission from well localized active surface regions (without supporting 3-D model computations, however). Based on the first, recently developed 3-D gas dynamical model of P/Halley’s activity, we have been shown that jet features can be reproduced assuming a homogeneous dusty ice nucleus surface. The dust in the collisional near nuclear coma is concentrated along the gas flow discontinuities resulting from the complicated surface orography, creating the visual impression of dust jets. We present here the results of these calculations for the near nucleus dust distributions, and we compare them with the direct observations made during the three Halley flybys (Vega 1, Vega 2, and Giotto).