Adding particle collisions to the formation of asteroids and Kuiper belt objects via streaming instabilities

By Anders Johansen, A. Youdin, Y. Lithwick. 2011

142 citations recorded by the source corpus.

Modelling the formation of super-km-sized planetesimals by gravitational collapse of regions overdense in small particles requires numerical algorithms capable of handling simultaneously hydrodynamics, particle dynamics and particle collisions. While the initial phases of radial contraction are dictated by drag forces and gravity, particle collisions become gradually more significant as filaments contract beyond Roche density. Here we present a new numerical algorithm for treating momentum and energy exchange in collisions between numerical superparticles representing a high number of physical particles. We adopt a Monte Carlo approach where superparticle pairs in a grid cell collide statistically on the physical collision time-scale. Collisions occur by enlarging particles until they touch and solving for the collision outcome, accounting for energy dissipation in inelastic collisions. We demonstrate that superparticle collisions can be consistently implemented at a modest computational cost. In protoplanetary disc turbulence driven by the streaming instability, we argue that the relative Keplerian shear velocity should be subtracted during the collision calculation. If it is not subtracted, density inhomogeneities are too rapidly diffused away, as bloated particles exaggerate collision speeds. Local particle densities reach several thousand times the mid-plane gas density. We find efficient formation of gravitationally bound clumps, with a range of masses corresponding to contracted radii from 100 to 400 km when applied to the asteroid belt and 150 to 730 km when applied to the Kuiper belt, extrapolated using a constant self-gravity parameter. The smaller planetesimals are not observed at low resolution, but the masses of the largest planetesimals are relatively independent of resolution and treatment of collisions.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/d1566824c3a6ca32db339cdf3cdf5b49aa533112

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In Astronomy and Astrophysics

Citations in the corpus

Rapid growth of gas-giant cores by pebble accretion (2012, methodology): “Theoretical models of planet formation show that these large seeds of approximately Ceres-size can form by self-gravity after clumping by the streaming instability (Johansen et al. 2007, 2012), so the pebble accretion scenario fits well with the formation of planetesimals by self-gravity.”
Confronting the Challenge of Modeling Cloud and Precipitation Microphysics (2020, methodology): “Li et al. (2017) confirmed that the performance of AON is better than Johansen et al. (2012), but direct comparison with other algorithms remains to be assessed.”
Dust Evolution and the Formation of Planetesimals (2016, background): “Particle concentration by the streaming instability can reach at least several thousand times the local gas density (Bai & Stone 2010; Johansen et al. 2012).”
Concentrating small particles in protoplanetary disks through the streaming instability (2016, background): “…driven by the streaming instability have significantly reduced radial drift speeds and thus longer radial drift time-scales, but also planetesimals can form by direct gravitational collapse within these dense filaments (Johansen et al. 2012, 2015; Simon et al. 2016, 2017; Schäfer et al. 2017).”
The primordial nucleus of comet 67P/Churyumov-Gerasimenko (2015, background): “The former value corresponds to D ≈ 900 km if collapsing to a single body (Johansen et al. 2012).”
Forming the cores of giant planets from the radial pebble flux in protoplanetary discs (2014, background): “…initial cores could be the result of streaming instabilities in the coupled motion between pebbles and gas, leading to the formation of planetesimals of about ∼0.1 Mt (Johansen et al. 2012), aided by continued growth by pebble accretion in the so-called drift branch (Lambrechts & Johansen 2012).”
THE MASS AND SIZE DISTRIBUTION OF PLANETESIMALS FORMED BY THE STREAMING INSTABILITY. I. THE ROLE OF SELF-GRAVITY (2015, methodology): “Note that with the exception of one of the simulations with G̃ = 0.1, the Johansen et al. (2012) simulations included collision microphysics.”
In search of the source of asteroid (101955) Bennu: Applications of the stochastic YORP model (2015, background): “This parent body was created by planetesimal formation mechanisms that may have involved the turbulent concentration of very small bodies in the primordial solar nebula (e.g., Johansen et al., 2007, 2012; Cuzzi et al., 2010).”