  Explaining the origin of the orbit of 2000 CR105 (a ~ 230AU, q ~ 45AU) is a
major test for our understanding of the primordial evolution of the outer Solar
System. Gladman et al. (2001) showed that this objects could not have been a
normal member of the scattered disk that had its perihelion distance increased
by chaotic diffusion. In this paper we explore four seemingly promising
mechanisms for explaining the origin of the orbit of this peculiar object: (i)
the passage of Neptune through a high-eccentricity phase, (ii) the past
existence of massive planetary embryos in the Kuiper belt or the scattered
disk, (iii) the presence of a massive trans-Neptunian disk at early epochs
which exerted tides on scattered disk objects, and (iv) encounters with other
stars. Of all these mechanisms, the only one giving satisfactory results is the
passage of a star. Indeed, our simulations show that the passage of a solar
mass star at about 800 AU only perturbs objects with semi-major axes larger
than roughly 200 AU to large perihelion distances. This is in good agreement
with the fact that 2000 CR105 has a semi-major axis of 230AU and no other
bodies with similar perihelion distances but smaller semi-major axes have yet
been discovered. The discovery of 2003 VB12, (a=450AU, q=75AU) announced a few
days before the submission of this paper, strengthen our conclusions.
