Transition elements between comets and asteroids .2. From the Kuiper belt to NEO orbits

In this paper we study the evolution of a comet nucleus taking into account its orbital evolution. It is assumed that the nucleus undergoes several close encounters with Giant Planets and its final orbit is that of the near-Earth object 4015 Wilson-Harrington. In paper I we presented results of a comet evolution model establishing the conditions under which the nucleus becomes dormant or extinct; we also identified a range of physical conditions leading to long-lasting activity that inexorably lead to the consumption of the icy material. The assumption in paper I was that the nucleus model is composed of a mixture of ices of water, CO2, and CO and dust particles; the H2O ice is initially crystalline. In this paper we analyze if the initial status of ice, the presence of CO, and the spin period affect the evolutionary history of the body, and if part of the original material is preserved in the inner part of the nucleus when the comet becomes a short-period comet. (C) 1997 Academic Press.