Near infrared observations of comet Halley from Vega 2

Abstract

Spatial distribution of the continuum radiation in the range of 0.95–1.9 μm presumes total dust production rate of the comet of 10 ρ tonne s −1 ( ρ is the dust material density) and its angular distribution proportional cos ϕ. Observations of the water vapor band at 1.38 μ m reveal strong jets, their time shift from the dust jet measured in situ is consistent with gas velocity of 0.82±0.1 km s −1 and dust velocity of 0.55±0.08 km s −1. The OH vibrational-rotational bands observed are excided directly via photolysis of water vapor. Water vapor production rate deduced from the H 2O band and OH band intensities is 8×10 29 s −1. Intensity of the CN(0,0) band result in the CN column density of 9×10 12 cm −2, i.e. larger by a factor of 3 than given by the violet band.