author={David Nesvorn{\'y} and Andrew N. Youdin and Derek C. Richardson},
  journal={The Astronomical Journal},
  pages={785 - 793}
A large fraction of ∼100 km class low-inclination objects in the classical Kuiper Belt (KB) are binaries with comparable masses and a wide separation of components. A favored model for their formation is that they were captured during the coagulation growth of bodies in the early KB. However, recent studies have suggested that large, ≳100 km objects can rapidly form in the protoplanetary disks when swarms of locally concentrated solids collapse under their own gravity. Here, we examine the… 

Trans-Neptunian binaries as evidence for planetesimal formation by the streaming instability

A critical step toward the emergence of planets in a protoplanetary disk is the accretion of planetesimals, bodies 1–1,000 km in size, from smaller disk constituents. This process is poorly

Dynamical Implantation of Blue Binaries in the Cold Classical Kuiper Belt

Colors and binarity provide important constraints on the Kuiper Belt formation. The cold classical objects at radial distance r = 42–47 au from the Sun are predominantly very red (spectral slope s >

Kuiper belt: Formation and evolution

Binary survival in the outer solar system

Binary Planetesimal Formation from Gravitationally Collapsing Pebble Clouds

Planetesimals are compact astrophysical objects roughly 1–1000 km in size, massive enough to be held together by gravity. They can grow by accreting material to become full-size planets.


The widely separated, near-equal mass binaries hosted by the cold classical Kuiper Belt are delicately bound and subject to disruption by many perturbing processes. We use analytical arguments and

Investigating gravitational collapse of a pebble cloud to form transneptunian binaries

Context. A large fraction of transneptunian objects are found in binary pairs, ~30% in the cold classical population between ahel ~ 39 and ~48 AU. Observationally, these binaries generally have

Turbulence Sets the Length Scale for Planetesimal Formation: Local 2D Simulations of Streaming Instability and Planetesimal Formation

The trans-Neptunian object 2014 MU69, named Arrokoth, is the most recent evidence that planetesimals did not form by successive collisions of smaller objects, but by the direct gravitational collapse



Formation of Kuiper Belt Binaries

The discovery that a substantial fraction of Kuiper Belt objects (KBOs) exists in binaries with wide separations and roughly equal masses has motivated a variety of new theories explaining their

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

It is shown 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) and the loss of energy needed to stabilize the binary orbit can occur through dynamical friction from surrounding small bodies, or through the gravitational scattering of a third large body.

The formation of Kuiper-belt binaries through exchange reactions

The only required assumption is that the TNOs were initially formed through gravitational instabilities in the protoplanetary dust disk, and the basis of the mechanism is an exchange reaction in which a binary whose primary component is much more massive than the secondary interacts with a third body, whose mass is comparable to that of the primary.

Formation of Kuiper-belt binaries through multiple chaotic scattering encounters with low-mass intruders

The discovery that many trans-Neptunian objects exist in pairs, or binaries, is proving invaluable for shedding light on the formation, evolution and structure of the outer Solar system. Based on

The Ratio of Retrograde to Prograde Orbits: A Test for Kuiper Belt Binary Formation Theories

With the discovery of Kuiper Belt binaries that have wide separations and roughly equal masses, new theories were proposed to explain their formation. Two formation scenarios were suggested by

The binary Kuiper-belt object 1998 WW31

It is reported that the Kuiper-belt object 1998 WW31 is binary with a highly eccentric orbit (eccentricity e ≈ 0.8) and a long period (about 570 days), very different from the Pluto/Charon system, which was hitherto the only previously known binary in theKuiper belt.

Towards initial mass functions for asteroids and Kuiper Belt Objects

Toward Planetesimals: Dense Chondrule Clumps in the Protoplanetary Nebula

We outline a scenario that traces a direct path from freely floating nebula particles to the first 10-100 km sized bodies in the terrestrial planet region, producing planetesimals that have

Planetesimal Formation by Gravitational Instability

We investigate the formation of planetesimals via the gravitational instability of solids that have settled to the midplane of a circumstellar disk. Vertical shear between the gas and a subdisk of

Rapid planetesimal formation in turbulent circumstellar disks

It is reported that boulders can undergo efficient gravitational collapse in locally overdense regions in the midplane of the disk, and it is found that gravitationally bound clusters form with masses comparable to dwarf planets and containing a distribution of boulder sizes.