The Near-Nuclear Coma of Comet Halley in March 1986

Abstract

The cameras carried onboard the flyby missions to comet P/Halleyin 1986 imaged the near nuclear jet activity fromseveral spatial directions. The observed, very structured near nucleardust jets were considered at that timeas 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 ofP/Halley's activity,we have been shown that jet features can be reproduced assuming ahomogeneous dusty icenucleus surface. The dust in the collisional near nuclear comais concentrated along the gas flow discontinuities resulting from thecomplicated surface orography, creating the visual impression ofdust jets. We present here the results of these calculations forthe near nucleus dust distributions,and we compare them with the direct observations made during thethree Halley flybys (Vega 1, Vega 2, and Giotto).