Rapid Growth of Asteroids Owing to Very Sticky Interstellar Organic Grains

Kouchi, Akira; Kudo, Tatsuyuki; Nakano, Hideyuki; Arakawa, Masahiko; Watanabe, Naoki; Sirono, Sin-iti; Higa, Michiya; Maeno, Norikazu

doi:10.1086/339618

Cited by 71 publications

(78 citation statements)

References 17 publications

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“…in enhancing the stickiness of the material and thereby potentially opening new growth channels. As for organic materials, Kouchi et al (2002) found an enhanced sticking of cm-sized bodies covered with a 1 mm thick layer of organic material at velocities as high as 500 cm s −1 and at a temperature of ∼250 K. Icy materials are also believed to have an enhanced sticking efficiency compared to silicatic materials. Hatzes et al (1991) collided 5 cm diameter solid ice spheres, which were covered with a 10-100 μm thick layer of frost.…”

Section: Influence Of the Adopted Materials Propertiesmentioning

confidence: 99%

The outcome of protoplanetary dust growth: pebbles, boulders, or planetesimals?

Zsom¹,

Ormel²,

Blum

et al. 2010

A&A

480

632

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Context. The growth processes from protoplanetary dust to planetesimals are not fully understood. Laboratory experiments and theoretical models have shown that collisions among the dust aggregates can lead to sticking, bouncing, and fragmentation. However, no systematic study on the collisional outcome of protoplanetary dust has been performed so far, so that a physical model of the dust evolution in protoplanetary disks is still missing. Aims. We intend to map the parameter space for the collisional interaction of arbitrarily porous dust aggregates. This parameter space encompasses the dust-aggregate masses, their porosities and the collision velocity. With such a complete mapping of the collisional outcomes of protoplanetary dust aggregates, it will be possible to follow the collisional evolution of dust in a protoplanetary disk environment. Methods. We use literature data, perform laboratory experiments, and apply simple physical models to get a complete picture of the collisional interaction of protoplanetary dust aggregates. Results. We found four different kinds of sticking, two kinds of bouncing, and three kinds of fragmentation as possible outcomes in collisions among protoplanetary dust aggregates. Our best collision model distinguishes between porous and compact dust. We also differentiate between collisions among similar-sized and different-sized bodies. All in all, eight combinations of porosity and mass ratio can be discerned. For each of these cases, we present a complete collision model for dust-aggregate masses between 10 −12 and 10 2 g and collision velocities in the range of 10 −4 . . . 10 4 cm s −1 for arbitrary porosities. This model comprises the collisional outcome, the mass(es) of the resulting aggregate(s) and their porosities. Conclusions. We present the first complete collision model for protoplanetary dust. This collision model can be used for the determination of the dust-growth rate in protoplanetary disks.

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Section: Influence Of the Adopted Materials Propertiesmentioning

confidence: 99%

The outcome of protoplanetary dust growth: pebbles, boulders, or planetesimals?

Zsom¹,

Ormel²,

Blum

et al. 2010

A&A

480

632

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“…Within the last years it was shown experimentally and theoretically that millimetre to centimetresize aggregates form on very short timescales independent from the disc model (Dominik & Tielens 1997;Blum et al 2006;Blum & Wurm 2008). Icy and/or organic materials might aid these growth processes by enhancing the stickiness of aggregates (Bridges et al 1996;Kouchi et al 2002). With increasing aggregate size, velocities between different size aggregates become larger, bodies get more and more compact and bouncing and fragmentation play an important role in further collisions.…”

Section: Introductionmentioning

confidence: 99%

Decimetre dust aggregates in protoplanetary discs

Teiser¹,

Wurm²

2009

A&A

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The growth of planetesimals is an essential step in planet formation. Decimetre-size dust agglomerates mark a transition point in this growth process. In laboratory experiments we simulated the formation, evolution, and properties of decimetre-scale dusty bodies in protoplanetary discs. Small sub-mm size dust aggregates consisting of micron-size SiO 2 particles randomly interacted with dust targets of varying initial conditions in a continuous sequence of independent collisions. Impact velocities were 7.7 m/s on average and in the range expected for collisions with decimetre bodies in protoplanetary discs. The targets all evolved by forming dust crusts with up to several cm thickness and a unique filling factor of 31% ± 3%. A part of the projectiles sticks directly. In addition, some projectile fragments slowly return to the target by gravity. All initially porous parts of the surface, i.e. built from the slowly returning fragments, are compacted and firmly attached to the underlying dust layers by the subsequent impacts. Growth is possible at impact angles from 0• (central collision) to 70• . No growth occurs at steeper dust surfaces. We measured the velocity, angle, and size distribution of collision fragments. The average restitution coefficient is 3.8% or 0.29 m/s ejection velocity. Ejecta sizes are comparable to the projectile sizes. The high filling factor is close to the most compact configuration of dust aggregates by local compression (∼33%). This implies that the history of the surface formation and target growth is completely erased. In view of this, the filling factor of 31% seems to be a universal value in the collision experiments of all self-consistently evolving targets at the given impact velocities. We suggest that decimetre and probably larger bodies can simply be characterised by one single filling factor. While gravity dominates re-accretion in the experiments, small fragments will be re-accreted as well in protoplanetary discs by gas drag at the given low ejection velocities. The accretion efficiency in planetesimal growth is model dependent. However, a small fraction of small particles re-accreted by gas flow or direct sticking readily allows growth of dusty bodies in protoplanetary discs in the decimetre range.

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“…Although heating experiments have already been performed using silicates (e.g., Hashimoto et al, 1979) and ices (e.g., Bar-Nun et a!., 1995;Kouchi, 1990) in a vacuum, experiments involving organic material have not been attempted. Therefore, the present authors recently performed heating experiments on an analogue ofinterstellar organic matter using chemical reagents (Kouchi et al, 2002;Nakano, unpubl. data).…”

Section: Introductionmentioning

confidence: 99%

“…Collision experiments have been carried out for silicates (e.g., Hartmann, 1978;Blum and Muench, 1993;Wurm and Blum, 1998;Poppe et al, 2000) and ice grains (e.g., Bridges et al, 1984;Hatzes et al, 1988;Higa et al, 1998), but not for organic material. The present authors therefore performed collision experiments involving organic matter in order to understand the effects of organic matter on the coagulation of dust grains (Kouchi et al, 2002).…”

Section: Introductionmentioning

confidence: 99%

The role of sticky interstellar organic material in the formation of asteroids

Kudo

Kouchi

Arakawa

et al. 2002

Meteorit & Planetary Scien

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Abstract-Collision experiments and measurements of viscoelastic properties were performed involving an interstellar organic material analogue to investigate the growth of organic grains in the protosolar nebula. The organic material was found to be stickiest at a radius ofbetween 2.3 and 3.0 AU, with a maximum sticking velocity of 5 m s-1 for millimeter-size organic grains. This stickiness is considered to have resulted in the very rapid coagulation of organic grain aggregates and subsequent formation of planetesimals in the early stage of the turbulent accretion disk. The planetesimals formed in this region appear to be represent achondrite parent bodies. In contrast, the formation of planetesimals at <2.1 and >3.0 AU begins with the establishment of a passive disk because silicate and ice grains are not as sticky as organic grains.

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Rapid Growth of Asteroids Owing to Very Sticky Interstellar Organic Grains

Cited by 71 publications

References 17 publications

The outcome of protoplanetary dust growth: pebbles, boulders, or planetesimals?

The outcome of protoplanetary dust growth: pebbles, boulders, or planetesimals?

Decimetre dust aggregates in protoplanetary discs

The role of sticky interstellar organic material in the formation of asteroids

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