A study of the original orbits of "hyperbolic" comets

Abstract

The problem of incoming orbits for single-apparition comets is investigated. In this context the effect of acceleration on cometary dynamics was analyzed for the sample of 33 hyperbolic comets. The orbital elements of each cometary orbit were determined by the least squares procedure based on positional observations. These osculating orbital elements serve as a basis for the determination of the incoming orbits. The new method of estimating the uncertainties of based on a statistical approach to the orbit determinations is applied. For sixteen comets it was possible to determine the effects and original non-gravitational orbits. We show that for almost all the comets with detectable effects the incoming barycentric orbits changed from to elliptical when the effects were included. However, it was also ascertained that excess velocity at great distance are not cancelled by the acceleration itself. We show that the effects are responsible for small modifications of the osculating elements (mainly eccentricity), which are sufficient, however, to obtain the elliptic original orbits for comets recognized in the literature as hyperbolic.