A Collisional Family in the Classical Kuiper Belt
Abstract
The dynamical evolution of classical Kuiper belt objects (CKBOs) is divided into two parts, according to the secular theory of test particle orbits. The first part is a forced oscillation driven by the planets, while the second part is a free oscillation whose amplitude is determined by the initial orbit of the test particle. We extract the free orbital inclinations and free orbital eccentricities from the osculating elements of 125 known CKBOs. The free inclinations of 32 CKBOs strongly cluster about 2° at orbital semimajor axes between 44 and 45 AU. We propose that these objects comprise a collisional family, the first so identified in the Kuiper belt. Members of this family are plausibly the fragments of an ancient parent body having a minimum diameter of ~800 km. This body was disrupted upon colliding with a comparably sized object and generated ejecta having similar free inclinations. Our candidate family is dynamically akin to a subfamily of Koronis asteroids located at semimajor axes less than 2.91 AU; both families exhibit a wider range in free eccentricity than in free inclination, implying that the relative velocity between parent and projectile prior to impact lay mostly in the invariable plane of the solar system. We urge more discoveries of new CKBOs, to test the reality of our candidate family, and more physical studies of candidate family members, to probe the heretofore unseen interior of a massive, primitive planetesimal.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- July 2002
- DOI:
- 10.1086/342089
- arXiv:
- arXiv:astro-ph/0205275
- Bibcode:
- 2002ApJ...573L..65C
- Keywords:
-
- Celestial Mechanics;
- Comets: General;
- Kuiper Belt;
- Minor Planets;
- Asteroids;
- Astrophysics
- E-Print:
- final revised version, accepted to ApJ Letters, includes minor caveat regarding Koronis asteroid family