[SunkenCiv]

Big-orbit Object Confounds Dynamicists
Source: Sky & Telescope Magazine
Published: Thursday, April 5 2001 Author: J. Kelly Beatty
Posted on 04/07/2001 11:46:54 PDT by vannrox
http://www.freerepublic.com/forum/a3acf609e1367.htm

"In the months that followed, an international team led by Brett Gladman (Nice Observatory) quietly tracked the dim interloper. Thanks to their year-long pursuit, it's now clear that 2000 CR105 has a highly eccentric orbit that stretches out to roughly 400 a.u. -- more than 10 times Pluto's mean distance from the Sun and far larger than that of any known Kuiper Belt object. But more puzzling to dynamicists is the orbit's perihelion distance. At 44.5 a.u. (6.7 billion km), it is well beyond the perturbing influence of Neptune, whose gravity has flung countless other bodies out to the solar system's most distant fringes. So how did 2000 CR105 end up stranded out there?"

[SunkenCiv]

[source]

Scenarios for the Origin of the Orbits of the Trans-Neptunian Objects 2000 CR105 and 2003 VB12 (Sedna)

Alessandro Morbidelli¹ and Harold F. Levison²

¹ Observatoire de la Côte d'Azur, Boulevard de l'Observatoire, B.P. 4229, 06304 Nice Cedex 4, France
² Southwest Research Institute, 1050 Walnut St., Suite 400, Boulder, CO 80302, USA

Explaining the origin of the orbits of 2000 CR₁₀₅ ( AU,  AU) and 2003 VB₁₂ (a=531 AU, q=74 AU, unofficially known as Sedna) is a major test for our understanding of the primordial evolution of the outer Solar System. Gladman et al. (2001) showed that 2000 CR105 could not have been a normal member of the scattered disk that had its perihelion distance increased by chaotic diffusion. The same conclusion also clearly applies to 2003 VB12. In this paper we explore five seemingly promising mechanisms for explaining the origin of the orbits of these peculiar objects: (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 that perturbed high-inclined scattered disk objects, (iv) encounters with other stars that perturbed the orbits of some of the Solar System's trans-Neptunian planetesimals, and (v) the capture of extra-solar planetesimals from low mass stars or brown dwarfs encountering the Sun. Of all these mechanisms, the ones giving the most satisfactory results are those related to the passages of stars (iv and v). An important advantage of both stellar passage scenarios is that all the resulting objects with large perihelion distances also have large semi-major axes. This is in good agreement with the fact that 2000 CR₁₀₅ and 2003 VB₁₂ have semi-major axes larger than 200 AU and no other bodies with similar perihelion distances but smaller semi-major axes have yet been discovered. We favor (iv), since it produces an orbital element distribution that is more consistent with the observations, unless 2000 CR₁₀₅ and 2003 VB₁₂ represent a population more massive than a few tenths of an Earth mass, in which case (iv) is not viable.

To appear in: The Astronomical Journal

Preprints on the web at http://www.boulder.swri.edu/~hal/CR105.html
and http://www.arXiv.org/abs/astro-ph/0403358