Gravoturbulent Formation of Planetesimals

By Anders Johansen, H. Klahr, Th. Henning. 2005

143 citations recorded by the source corpus.

We explore the effect of magnetorotational turbulence on the dynamics and concentrations of boulders in local box simulations of a sub-Keplerian protoplanetary disk. The solids are treated as particles, each with an independent space coordinate and velocity. We find that the turbulence has two effects on the solids. (1) Meter and decameter bodies are strongly concentrated, locally up to a factor of 100 times the average dust density, whereas decimeter bodies only experience a moderate density increase. The concentrations are located in large-scale radial gas density enhancements that arise from a combination of turbulence and shear. (2) For meter-sized boulders, the concentrations cause the average radial drift speed to be reduced by 40%. We find that the densest clumps of solids are gravitationally unstable under physically reasonable values for the gas column density and for the dust-to-gas ratio due to sedimentation. We speculate that planetesimals can form in a dust layer that is not in itself dense enough to undergo gravitational fragmentation, and that fragmentation happens in turbulent density fluctuations in this sublayer.

Subfields: Astronomy and Astrophysics, Fluid Flow and Transfer Processes

View Paper: https://www.semanticscholar.org/paper/180f6de10b1d962a50bb6daaa35a89792978b518

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

In Fluid Flow and Transfer Processes

Citations in the corpus

Forming Planetesimals in Solar and Extrasolar Nebulae (2009, background): “20 SUMMARY AND OUTLOOK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21”
Toward Planetesimals: Dense Chondrule Clumps in the Protoplanetary Nebula (2008, background): “A third class of scenario suggests that a complex interplay between several nonlinear processes - turbulence, pressure gradients, and gravity - may concentrate appropriately sized particles and lead to planetesimal growth (Cuzzi et al 2001, 2005, 2007; Johansen et al 2006, 2007).”
FORMATION OF KUIPER BELT BINARIES BY GRAVITATIONAL COLLAPSE (2010, background): “However, particles can also clump in a turbulent flow (e.g., Cuzzi et al. 2001, 2008; Johansen et al. 2006).”
Standing on the shoulders of giants : Trojan Earths and vortex trapping in low mass self-gravitating protoplanetary disks of gas and solids (2008, methodology): “Johansen et al. (2006a) simulated the flow in an MRI-active local box using a statistically significant number of particles (106), and showed that the particle concentration is high enough to achieve critical densities.”
Gas- and dust evolution in protoplanetary disks (2010, background): “Johansen et al. (2006) found a reduction of the radial drift velocity of up to 40% for meter-sized particles.”
ZONAL FLOWS AND LONG-LIVED AXISYMMETRIC PRESSURE BUMPS IN MAGNETOROTATIONAL TURBULENCE (2008, background): “Such a convergence zone can quickly accumulate rocks and boulders, enhancing the local density enough to trigger gravitational instabilities which form planetesimals or dwarf planets in a very short time (Youdin & Shu 2002; Johansen et al. 2006, 2007).”
Dust flow in gas disks in the presence of embedded planets (2006, background): “A mixture of equal amounts of gas and dust is subject to streaming instabilities (Youdin & Goodman 2005), and it is not clear whether the resulting turbulent structure will prohibit gravitational instabilities or enhance them (Johansen et al. 2006).”
Dust settling in local simulations of turbulent protoplanetary disks (2006, background): “Johansen et al. (2006) and Fromang & Nelson (2005) studied the radial migration of centimeter and meter size bodies in turbulent disk models and found that dust trapping in local pressure maxima could be an important confining effect.”
A simple model for the evolution of the dust population in protoplanetary disks (2012, background): “Once these over-densities reach Toomre unstable values and exceed the local Roche density, planetesimal formation via self gravity in the dust layer is the consequence (Johansen et al. 2006).”
Dynamics of pebbles in the vicinity of a growing planetary embryo: hydro-dynamical simulations (2012, methodology): “More specifically, this model builds on the recent planetesimal formation model (Youdin & Goodman 2005; Johansen et al. 2006, 2007, 2009) in which large planetesimals (with sizes from ∼100 up to ∼1000 km) form by the collapse of a self-gravitating clump of pebbles, concentrated to high densities by…”
How to form planetesimals from mm-sized chondrules and chondrule aggregates (2015, background): “These regions can quickly accumulate meter- and decimeter-sized bodies, and for meter-sized boulders, the concentrations can significantly reduce the radial drift caused by friction with the surrounding gas (Johansen et al. 2006, 2007).”
Particle Stirring in Turbulent Gas Disks: Including Orbital Oscillations (2007, methodology): “Simulations have now begun to include the dynamical feedback of particles on gas dynamics (Johansen et al., 2006a; Johansen and Youdin, 2007).”