Model calculations of nongravitational forces on short-period comets. I - Low-obliquity case. II - High-obliquity case

In view of the rich material of determinations of non-gravitational forces on comets that already exists and may soon be brought to higher precision using space astrometry, and being aware of the possibilities of using this in order to deduce information on the physical properties of cometary nuclei, the authors present a study of the behaviour of these forces as predicted by thermal models of the nuclei. These models use a very simplified picture of the cometary nucleus as a homogeneous and isotropic sphere made up of H₂O ice and dust grains, but they explicitly include the effects of heat conduction on both the orbital and rotational time scales. In particular the authors study the variation of the radial, transverse and normal force components with distance from the Sun for various kinds of short-period comet orbits, represented by comets P/Kopff, P/Gehrels 3, P/Boethin, P/Crommelin and P/Halley.