The angular momentum of two collided rarefied preplanetesimals and the formation of binaries

Abstract

This paper studies the mean angular momentum associated with the collision of two celestial objects in the earliest stages of planet formation. Of primary concern is the scenario of two rarefied preplanetesimals (RPPs) in circular heliocentric orbits. The theoretical results are used to develop models of binary or multiple system formation from RPPs, and explain the observation that a greater fraction of binaries originated farther from the Sun. At the stage of RPPs, small-body satellites can form in two ways: a merger between RPPs can have two centers of contraction, or the formation of satellites from a disc around the primary or the secondary. Formation of the disc can be caused by that the angular momentum of the RPP formed by the merger is greater than the critical angular momentum for a solid body. One or several satellites of the primary (moving mainly in low-eccentricity orbits) can be formed from this disc at any separation less than the Hill radius. The first scenario can explain a system such as 2001 QW322 where the two components have similar masses but are separated by a great distance. In general, any values for the eccentricity and inclination of the mutual orbit are possible. Among discovered binaries, the observed angular momenta are smaller than the typical angular momenta expected for identical RPPs having the same total mass as the discovered binary and encountering each other in circular heliocentric orbits. This suggests that the population of RPPs underwent some contraction before mergers became common.

12 pages, Monthly Notices of Royal Astron. Society, in press

References in corpus (11)

• Rapid planetesimal formation in turbulent circumstellar discs
• Asteroids Were Born Big
• Particle Clumping and Planetesimal Formation Depend Strongly on Metallicity
• Towards planetesimals: dense chondrule clumps in the protoplanetary nebula
• Embryos grown in the dead zone: Assembling the first protoplanetary cores in low mass self-gravitating circumstellar disks of gas and solids
• Accretion and destruction of planetesimals in turbulent disks
• The Correlated Colors of Transneptunian Binaries
• Formation of Kuiper-belt binaries through multiple chaotic scattering encounters with low-mass intruders
• From Grains to Planetesimals: Les Houches Lecture
• Angular Momemtum of Binary Asteroids: Implication for their possible origin
• Binary formation and mass function variations in fragmenting discs with short cooling times

Cited by in corpus (6)

• Migration processes in the Solar System and their role in the evolution of the Earth and planets
• Probabilities of collisions of planetesimals from different regions of the feeding zone of the terrestrial planets with the forming planets and the Moon
• Formation of trans-Neptunian satellite systems at the stage of condensations
• Formation of embryos of the Earth and the Moon from the common rarefied condensation and their subsequent growth
• Origin of orbits of secondaries in the discovered trans-Neptunian binaries
• Angular momenta of collided rarefied preplanetesimals