Experimental Investigations on Aggregate-Aggregate Collisions in the Early Solar Nebula

Blum, Jürgen; Münch, M.

doi:10.1006/icar.1993.1163

Cited by 182 publications

(199 citation statements)

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“…The fragment masses follow a velocity-independent power law, with the largest fragment being a function of impact speed (Blum & Münch, 1993;Güttler et al, 2010). For the micrometer-sized spherical SiO 2 particles used in most of our experiments, the fragmentation boundary is at v c ≈ 1 m s −1 , remarkably close to the threshold velocity for sticking of the monomer grains (see Sect.…”

Section: A New Dust-aggregate Collision Modelmentioning

confidence: 62%

“…Previous experiments had shown that -even in the case of bouncing -a substantial part of the kinetic energy is dissipated, typically between 80% and 95% (Blum & Münch, 1993). Further experiments by Weidling et al (2009) showed that the energy is used to restructure the aggregates close to the surface, which leads to local compaction.…”

Section: A New Dust-aggregate Collision Modelmentioning

confidence: 99%

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Dust growth in protoplanetary disks — a comprehensive experimental/theoretical approach

Blum

2010

Res. Astron. Astrophys.

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More than a decade of dedicated experimental work on the collisional physics of protoplanetary dust has brought us to a point at which the growth of dust aggregates canfor the first time -be self-consistently and reliably modelled. In this article, the emergent collision model for protoplanetery dust aggregates as well as the numerical model for the evolution of dust aggregates in protoplanetary disks are reviewed. It turns out that, after a brief period of rapid collisional growth of fluffy dust aggregates to sizes of a few centimeters, the protoplanetary dust particles are subject to bouncing collisions, in which their porosity is considerably decreased. The model results also show that low-velocity fragmentation can reduce the final mass of the dust aggregates but that it does not trigger a new growth mode as discussed previously. According to the current stage of our model, the direct formation of kilometer-sized planetesimals by collisional sticking seems impossible so that collective effects, such as the streaming instability and the gravitational instability in dust-enhanced regions of the protoplanetary disk, are the best candidates for the processes leading to planetesimals.

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Section: A New Dust-aggregate Collision Modelmentioning

confidence: 62%

Section: A New Dust-aggregate Collision Modelmentioning

confidence: 99%

Dust growth in protoplanetary disks — a comprehensive experimental/theoretical approach

Blum

2010

Res. Astron. Astrophys.

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“…All simulations include collisions with a coefficient of restitution of = 0.3 (e.g Blum & Muench 1993), meaning that each collision leads to the dissipation of approximately 90% of the relative kinetic energy to deformation and heating of the colliding boulders. We include particle collisions here to obtain a more complete physical modelling.…”

Section: Collisionsmentioning

confidence: 99%

High-resolution simulations of planetesimal formation in turbulent protoplanetary discs

Johansen

Klahr

Henning

2011

A&A

131

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We present high-resolution computer simulations of dust dynamics and planetesimal formation in turbulence generated by the magnetorotational instability. We show that the turbulent viscosity associated with magnetorotational turbulence in a non-stratified shearing box increases when going from 256 3 to 512 3 grid points in the presence of a weak imposed magnetic field, yielding a turbulent viscosity of α ≈ 0.003 at high resolution. Particles representing approximately meter-sized boulders concentrate in large-scale high-pressure regions in the simulation box. The appearance of zonal flows and particle concentration in pressure bumps is relatively similar at moderate (256 3 ) and high (512 3 ) resolution. In the moderate-resolution simulation we activate particle self-gravity at a time when there is little particle concentration, in contrast with previous simulations where particle self-gravity was activated during a concentration event. We observe that bound clumps form over the next ten orbits, with initial birth masses of a few times the dwarf planet Ceres. At high resolution we activate self-gravity during a particle concentration event, leading to a burst of planetesimal formation, with clump masses ranging from a significant fraction of to several times the mass of Ceres. We present a new domain decomposition algorithm for particle-mesh schemes. Particles are spread evenly among the processors and the local gas velocity field and assigned drag forces are exchanged between a domain-decomposed mesh and discrete blocks of particles. We obtain good load balancing on up to 4096 cores even in simulations where particles sediment to the mid-plane and concentrate in pressure bumps.

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“…If the collisional energy of dust grains is high enough to disrupt the grains, dust grains cannot grow further. The threshold velocity of fragmentation is a few meters per second for silicate-like aggregates, much smaller than the typical highest collision velocity of 50 m s 1 in disks (Blum and Münch 1993;Blum and Wurm 2008;Wada et al 2007Wada et al , 2009Wada et al , 2013. Dust grains of some size ranges do not stick, but rather bounce Zsom et al 2010).…”

Section: Introductionmentioning

confidence: 87%

“…Although the threshold velocity of fragmentation does not depend on the aggregate mass, it depends on materials and the size of the monomers. Enormous efforts have been made with laboratory experiments that show that the threshold velocity of silicate grains is a few m s 1 (e.g., Blum and Münch 1993) and a few tens of m s 1 for ice (Gundlach and Blum 2015). In the series of numerical simulations (Wada et al 2007(Wada et al , 2011 where r 0 is the monomer radius (Wada et al 2013).…”

Section: Fragmentation Barriermentioning

confidence: 99%

Dust Coagulation with Porosity Evolution

Kataoka

2017

Formation, Evolution, and Dynamics of Young Solar Systems

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Theoretical studies, laboratory experiments, and numerical simulations have shown several barriers in planetesimal formation, including radial drift, fragmentation, and bouncing problems. Also, observations of protoplanetary disks have shown the radial drift problems of millimeter-sized bodies at the outer orbital radius. The key to solving these problems is understanding porosity evolution. Dust grains become fluffy by coagulation in protoplanetary disks and this alters both the dynamic and optical properties of dust aggregates. First, we revealed the overall porosity evolution from micron-sized dust grains to kilometer-sized planetesimals; dust grains form extremely porous dust aggregates, where the filling factor is 10 4 , and then they are compressed by their collisions, the disk gas, and their self-gravity. In the coagulation process, they circumvent all the barriers if the monomers are 0.1-m icy bodies. The mass and porosity of the final product are consistent with those of the comets, which are believed to be the remnants of planetesimals. We further performed coagulation simulations including porosity evolution. We found that planetesimals can form inside 10 AU, avoiding the radial drift barrier. Furthermore, we calculated the opacity evolution of porous dust aggregates and found that the observed radio emission could be explained either by compact dust grains or by fluffy dust aggregates.

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Experimental Investigations on Aggregate-Aggregate Collisions in the Early Solar Nebula

Cited by 182 publications

References 0 publications

Dust growth in protoplanetary disks — a comprehensive experimental/theoretical approach

Dust growth in protoplanetary disks — a comprehensive experimental/theoretical approach

High-resolution simulations of planetesimal formation in turbulent protoplanetary discs

Dust Coagulation with Porosity Evolution

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