A Caltech Library Service

Interactions among Noninteracting Particles in Planet Formation Simulations

Peng, Shirui and Batygin, Konstantin (2020) Interactions among Noninteracting Particles in Planet Formation Simulations. Astrophysical Journal Letters, 898 (2). Art. No. L46. ISSN 2041-8213.

PDF - Published Version
See Usage Policy.

[img] PDF - Submitted Version
See Usage Policy.


Use this Persistent URL to link to this item:


Over the course of recent decades, N-body simulations have become a standard tool for quantifying the gravitational perturbations that ensue in planet-forming disks. Within the context of such simulations, massive non-central bodies are routinely classified into "big" and "small" particles, where big objects interact with all other objects self-consistently, while small bodies interact with big bodies but not with each other. Importantly, this grouping translates to an approximation scheme where the orbital evolution of small bodies is dictated entirely by the dynamics of the big bodies, yielding considerable computational advantages with little added cost in terms of astrophysical accuracy. Here we point out, however, that this scheme can also yield spurious dynamical behavior where, even in the absence of big bodies within a simulation, indirect coupling among small bodies can lead to excitation of the constituent "non-interacting" orbits. We demonstrate this self-stirring by carrying out a sequence of numerical experiments, and confirm that this effect is largely independent of the time-step or the integration algorithm employed. Furthermore, adopting the growth of angular momentum deficit as a proxy for dynamical excitation, we explore its dependence on time, the cumulative mass of the system, as well as the total number of particles present in the simulation. Finally, we examine the degree of such indirect excitation within the context of conventional terrestrial planet formation calculations, and conclude that although some level of caution may be warranted, this effect plays a negligible role in driving the simulated dynamical evolution.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper ItemCode
Peng, Shirui0000-0002-4616-4604
Batygin, Konstantin0000-0002-7094-7908
Alternate Title:Interactions Among Non-Interacting Particles in Planet Formation Simulations
Additional Information:© 2020 The American Astronomical Society. Received 2020 June 3; revised 2020 July 11; accepted 2020 July 16; published 2020 July 31. We are grateful to Matthew J. Holman, Juliette C. Becker, Marguerite Epstein-Martin, Max Goldberg, Tobias Koehne and Elizabeth Bailey for insightful discussions. Additionally, we would like to thank Hanno Rein for providing a thorough and insightful referee report which led to a considerable improvement of the manuscript, as well as his assistance with implementation of numerical experiments. K.B. is grateful to the David and Lucile Packard Foundation and the Alfred P. Sloan Foundation for their generous support. Simulations in this paper made use of the REBOUND code which is freely available at
Group:Astronomy Department
Funding AgencyGrant Number
David and Lucile Packard FoundationUNSPECIFIED
Alfred P. Sloan FoundationUNSPECIFIED
Subject Keywords:Planet formation ; Solar system formation ; N-body simulations ; Dynamical friction
Issue or Number:2
Classification Code:Unified Astronomy Thesaurus concepts: Planet formation (1241); Solar system formation (1530); N-body simulations (1083); Dynamical friction (422)
Record Number:CaltechAUTHORS:20200731-122008435
Persistent URL:
Official Citation:Shirui Peng and Konstantin Batygin 2020 ApJL 898 L46
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:104679
Deposited By: Tony Diaz
Deposited On:31 Jul 2020 20:24
Last Modified:31 Jul 2020 20:24

Repository Staff Only: item control page