A Caltech Library Service

Formation of Kuiper-belt binaries by dynamical friction and three-body encounters

Goldreich, Peter and Lithwick, Yoram and Sari, Re’em (2002) Formation of Kuiper-belt binaries by dynamical friction and three-body encounters. Nature, 420 (6916). pp. 643-646. ISSN 0028-0836.

Full text is not posted in this repository. Consult Related URLs below.

Use this Persistent URL to link to this item:


The Kuiper belt is a disk of icy bodies that orbit the Sun beyond Neptune; the largest known members are Pluto and its companion Charon. A few per cent of Kuiper-belt bodies have recently been found to be binaries with wide separations and mass ratios of the order of unity. Collisions were too infrequent to account for the observed number of binaries, implying that these binaries formed through collisionless interactions mediated by gravity. These interactions are likely to have been most effective during the period of runaway accretion, early in the Solar System's history. Here we show that a transient binary forms when two large bodies penetrate one another's Hill sphere (the region where their mutual forces are larger than the tidal force of the Sun). The loss of energy needed to stabilize the binary orbit can then occur either through dynamical friction from surrounding small bodies, or through the gravitational scattering of a third large body. Our estimates slightly favour the former mechanism. We predict that five per cent of Kuiper-belt objects are binaries with apparent separations greater than 0.2 arcsec, and that most are in tighter binaries or systems of higher multiplicity.

Item Type:Article
Related URLs:
URLURL TypeDescription DOIArticle ReadCube access
Sari, Re’em0000-0002-1084-3656
Additional Information:© 2002 Nature Publishing Group. Received 29 August; accepted 17 October 2002. We thank S. Kenyon for discussions about the dynamics of accretion. This work was supported by the NSF and NASA. R.S. is supported by the Fairchild Foundation.
Funding AgencyGrant Number
Sherman Fairchild FoundationUNSPECIFIED
Issue or Number:6916
Record Number:CaltechAUTHORS:20130305-110107206
Persistent URL:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:37301
Deposited By: Tony Diaz
Deposited On:05 Mar 2013 23:53
Last Modified:03 Mar 2020 13:01

Repository Staff Only: item control page