JETS IN THE COMA OF COMET P/HALLEY IN MID-APRIL 1986

On 17 and 18 April 1986 sequences of narrow-band IHW filter CCD images of the coma of Comet P/Halley were obtained with the 2.2-m telescope at ESO La Silla/Chile. Image processing led to the detection of jet features in the coma which can be traced back to systematic irregularities in the isophote patterns of the original images. In total four jets were found on 17 April 1986 and three jets on 18 April 1986. Some of the jets were observed through the CN (C2 and C3) filters only, while others appear through all filters used. This finding supports ideas about the heterogeneity of the nuclear jet sources. The jet features in our observations may possibly be related to CN jets in the data of A'Hearn et al. (1986, Nature 324, 649-651 and European Space Agency Spec. Publ. 250, Vol. I, 483-486). They are also in good agreement with predictions of the geometric jet characteristics from Belton's nucleus rotation model for Halley's comet (1990, Icarus 86, 30-51). Our observations indicate source 3 of Belton's model as the origin of a major dust jet, while source 2 produced predominantly gaseous species (CN, C2, and C3). © 1992.