STELLAR PERTURBATIONS OF INNER-CORE COMETS AND THE IMPULSE APPROXIMATION

A new method has been developed to calculate the perturbations caused by passing stars on inner core comets. It is a modification of the imp ulse approximation in which the star path is split up and several part ial impulses are calculated, rather than taking a single impulse at cl osest approach. The new method is about 10-100 times faster than numer ical integration, with which it gives good agreement, In a second line of investigation, it is found that, for small changes, stellar pertur bations are as likely to reduce cometary perihelia as to increase them . Because the magnitude of a negative change in q is limited by an abs olute boundary at q = 0, a small number of very large positive delta q values will create the appearance of a positive tendency in changing q for many successive stellar perturbations.