Investigating Gravitational Collapse of a Pebble Cloud to form Transneptunian Binaries

Jamie Robinson, Wesley Fraser, Alan Fitzsimmons, Pedro Lacerda

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)

Abstract

Context. A large fraction of transneptunian objects are found in binary pairs, $\sim30\%$ in the cold classical population between $a_\mathrm{hel}\sim 39$ and $\sim48\, \mathrm{AU}$. Observationally, these binaries generally have components of similar size and colour. Previous work has shown that gravitational collapse of a pebble cloud is an efficient mechanism for producing such systems. Since the discovery of the bi-lobate nature of 2014 MU$_{69}$ (Arrokoth) there is also interest in gravitational collapse as a pathway to form contact binaries.

Aims. Our aim was to investigate the formation of binary systems via gravitational collapse, considering a wider range of binary masses than previous studies. We analysed in detail the properties of the bound systems that are formed and compared them to observations.

Methods. We performed $N$-body simulations of gravitational collapse of a pebble cloud using the \rebound package, with an integrator designed for rotating reference frames and robust collision detection. We conducted a deep search for gravitationally bound particles at the end of the gravitational collapse phase and tested their stability. For all systems produced, not just the most massive binaries, we investigated the population characteristics of their mass and orbital parameters.

Results. We found that gravitational collapse is an efficient producer of bound planetesimal systems. On average there were $\sim1.5$ bound systems produced per cloud, in the mass range studied here. As well as the large, equal-sized binaries, we found that gravitational collapse produces massive bodies with small satellites and low mass binaries with a high mass ratio. Gravitational collapse can create binary systems analogous to Arrokoth and collisions in a collapsing cloud should be gentle enough to preserve a bi-lobed structure.
Original language English A55 Astronomy & Astrophysics 643 https://doi.org/10.1051/0004-6361/202037456 Published - 03 Nov 2020

Keywords

• Kuiper belt: general
• Minor planets, asteroids: general
• Planets and satellites: formation

Fingerprint

Dive into the research topics of 'Investigating Gravitational Collapse of a Pebble Cloud to form Transneptunian Binaries'. Together they form a unique fingerprint.
• Investigating Gravitational Collapse of a Pebble Cloud to form Transneptunian Binaries: Supplementary Animation

Robinson, J. (Creator), Queen's University Belfast, 05 May 2020

Dataset

File
• The origin and evolution of Transneptunian binaries

Author: Robinson, J., Jul 2020

Supervisor: Fitzsimmons, A. (Supervisor), Fraser, W. (Supervisor), Lacerda, P. (Supervisor) & Sim, S. (Supervisor)

Student thesis: Doctoral ThesisDoctor of Philosophy

File