A Monte Carlo approach to the analysis of the dust tail of comet P/Halley

Abstract

A quantitative analysis of three wide-field photographs of Comet P/Halley obtained between 3 and 6 May 1986 has been carried out. The digitally processed maps were used as input for the Monte Carlo approach to interpreting cometary dust tails. The developed model considers the conditions of the ejection of the dust particles from the collision zone of the cometary coma, the time-averaged dust size distribution, and the dependency between the dust production rate and the heliocentric distance. The lack of any photometric standardization has not allowed an absolute value of the dust production rate to be obtained. The use of panchromatic plates without filters may cause ion plasma interference and therefore a certain biasing of the results. The adjustment procedure gives the model parameters in general agreement with the results of the investigations by Fulle et al. (1989, Astron. Astrophys. 201, 362–372) and by Cremonese and Fulle (1989, Icarus 80, 267–279), and the results of in situ experiments. The maximum value of the dust ejection velocity is 0.46 (±0.23) km sec −1 and is achieved generally after the perihelion passage. The dust ejection velocity dependency on the particle radius is very weak with a power index of −0.25 (±0.10). The dust number production rate varies with heliocentric distance as r −3.8(±0.7) and attains its maximum value for the true anomaly 8°. Power indices of the dust size distribution function are −3.22 (±0.36) and −3.71 (±0.22) for particles of radius less than and greater than 7.3 μm, respectively. These values are in good agreement with the time-averaged size distribution obtained for P/Halley by Fulle et al.