Models of the OH 18-cm line profiles of Comet Halley

In an attempt to better understand the kinematics of the cometary coma, the OH 18-cm line profiles observed during the recent apparition of Comet Halley were modeled. There are obviously many physical properties which are responsible for producing the observed line profiles. Such properties include the velocity distribution of the OH radicals, the lifetimes of the parents (hereafter assumed to be H2O) and daughters (OH), and the morphology and velocity of the outflow of parents from the nuclear region. The effect that the outflow of parents, specifically the parent outflow velocity, has on the mean velocity and the line width of the emergent profiles is reported. Nominal values are adopted for the input parameters and computed model line profiles, for comparison with the data of Schloerb and Claussen (1986). In general, reasonable agreement is found between the model profiles and the data, although some adjustments to the nominal input parameters may be required as a result of this effort. 10 references