Growth of planetesimals by impacts at ∼25 m/s

Wurm, Gerhard; Paraskov, Georgi; Krauß, Oliver

doi:10.1016/j.icarus.2005.04.002

Cited by 167 publications

(182 citation statements)

References 27 publications

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“…It was observed in experiments (Wurm et al, 2005) that this type of collision results in the attachment of part of the fluffy aggregate's mass to the compact particle. -B1: bouncing with compaction.…”

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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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: 99%

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

Blum

2010

Res. Astron. Astrophys.

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“…The coagulation outcome of collisions with f < 0.1 and 1 m s −1 ≤ ∆v < 25 m s −1 is explained by mass transfer or penetration (Wurm et al 2005). A map of collision outcomes in (∆v, a)-space is shown in Fig.…”

Section: Collisional Outcomesmentioning

confidence: 99%

“…Growth by coagulation can proceed via mass transfer as small impactors deposit part of their mass when hitting a large target particle (Wurm et al 2005). The resulting growth is nevertheless slow, resulting in the formation of 100 m scale planetesimals in the asteroid belt in 1 Myr (Windmark et al 2012); and growth rates would be even lower in the Kuiper belt.…”

Section: Introductionmentioning

confidence: 99%

Formation of pebble-pile planetesimals

Jansson

Johansen

2014

A&A

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Asteroids and Kuiper belt objects are remnant planetesimals from the epoch of planet formation. The first stage of planet formation is the accumulation of dust and ice grains into mm-and cm-sized pebbles. These pebbles can clump together through the streaming instability and form gravitationally bound pebble clouds. Pebbles inside such a cloud will undergo mutual collisions, dissipating energy into heat. As the cloud loses energy, it gradually contracts towards solid density. We model this process and investigate two important properties of the collapse: (i) the collapse timescale and (ii) the temporal evolution of the pebble size distribution. Our numerical model of the pebble cloud is zero-dimensional and treats collisions with a statistical method. We find that planetesimals with radii larger than ∼100 km collapse on the free-fall timescale of ∼25 years. Lower-mass clouds have longer pebble collision timescales and collapse much more slowly, with collapse times of a few hundred years for 10 km scale planetesimals and a few thousand years for 1 km scale planetesimals. The mass of the pebble cloud also determines the interior structure of the resulting planetesimal. The pebble collision speeds in low-mass clouds are below the threshold for fragmentation, forming pebble-pile planetesimals consisting of the primordial pebbles from the protoplanetary disk. Planetesimals above 100 km in radius, on the other hand, consist of mixtures of dust (pebble fragments) and pebbles which have undergone substantial collisions with dust and other pebbles. The Rosetta mission to the comet 67P/Churyumov-Gerasimenko and the New Horizons mission to Pluto will provide valuable information about the structure of planetesimals in the solar system. Our model predicts that 67P is a pebble-pile planetesimal consisting of primordial pebbles from the solar nebula, while the pebbles in the cloud which contracted to form Pluto must have been ground down substantially during the collapse.

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“…Smoothed particle hydrodynamic (SPH) simulations suggest the increase in the critical velocity for different-sized collisions (Meru et al 2013). Laboratory experiments report that porous aggregates consisting of micron-sized SiO 2 particles can grow when they are collided onto large (flat) targets at u col > 10 m s −1 (Wurm et al 2005;Teiser & Wurm 2009;Paraskov et al 2007). These experimental results suggest a positive effect of different-sized collisions on dust growth.…”

Section: Introductionmentioning

confidence: 99%

Growth efficiency of dust aggregates through collisions with high mass ratios

Wada

Tanaka

Okuzumi

et al. 2013

A&A

155

198

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Context. Collisional growth of dust aggregates is an essential process in forming planetesimals in protoplanetary disks, but disruption through high-velocity collisions (disruption barrier) could prohibit the dust growth. Mass transfer through very different-sized collisions has been suggested as a way to circumvent the disruption barrier. Aims. We examine how the collisional growth efficiency of dust aggregates with different impact parameters depends on the size and the mass ratio of colliding aggregates. Methods. We used an N-body code to numerically simulate the collisions of different-sized aggregates. Results. Our results show that high values for the impact parameter are important and that the growth efficiency averaged over the impact parameter does not depend on the aggregate size, although the growth efficiency for nearly head-on collisions increases with size. We also find that the averaged growth efficiency tends to increase with increasing mass ratio of colliding aggregates. However, the critical collision velocity, above which the growth efficiency becomes negative, does not strongly depend on the mass ratio. These results indicate that icy dust can grow through high-velocity offset collisions at several tens of m s −1 , the maximum collision velocity experienced in protoplanetary disks, whereas it is still difficult for silicate dust to grow in protoplanetary disks.

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Growth of planetesimals by impacts at ∼25 m/s

Cited by 167 publications

References 27 publications

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

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

Formation of pebble-pile planetesimals

Growth efficiency of dust aggregates through collisions with high mass ratios

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