Evolution of grains in a turbulent solar nebula

Weidenschilling, S. J.

doi:10.1016/0019-1035(84)90164-7

Cited by 223 publications

(205 citation statements)

References 18 publications

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“…Detailed calculations for the primordial solar nebula, carried out by Volk et al (1980), Weidenschilling (1984), Safronov and Vityazev (1985), and Markiewicz and Volk (1988), confirm the earlier estimate that small grains have relative velocities in the range of 1 cm-s -1 to 1 m-s -1 . Similar velocities are expected in dense interstellar clouds (Volk et al, 1980).…”

Section: Impact Velocities Of Grainssupporting

confidence: 63%

“…This effect, combined with fragmentation at velocities appreciably in excess of 5 x 10 3 cm-s -1 , suggests that comets can form only when VR < 5 X 10 3 cm-s -1 . Velocities increase for larger aggregates, and the calculations of Volk et al (1980) and Weidenschilling (1984) indicate VR will be ~ 10 4 cm-s" 1 for aggregates larger than about a kilometer. This suggests that nuclei composed of such size aggregates will not grow much larger and will start being depleted in volatiles.…”

Section: 3 Accumulation Of Fluffy Aggregatesmentioning

confidence: 91%

“…Larger velocities require that one aggregate be at least twice the size of the other. Limiting VR to be under 5 x 10 3 cm-s -1 is not a serious constraint for low-density aggregates, according to current theories of accumulation in the primordial nebula (Volk et al, 1980;Weidenschilling, 1984). …”

Section: 3 Accumulation Of Fluffy Aggregatesmentioning

confidence: 96%

“…It was pointed out by Donn and Sears (1963) that the required velocities, less than a few tenths of kilometers per second, would apply to small grains in the primordial solar nebula because of the efficiency of gas drag in slowing them down. Detailed calculations have been made by Volk et al (1980) and Weidenschilling (1984). It has recently been shown (Meakin and Donn, 1988) that because of the fractal nature of the aggregates, particles containing on the order of 10 4 grains would also be effectively slowed by the gas and have low impact velocities.…”

Section: Accumulation From Solid Grainsmentioning

confidence: 99%

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The Accumulation and Structure of Comets

Donn¹

1989

International Astronomical Union Colloquium

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ABSTRACT. The evidence for the accumulation of the terrestrial planets and comets from solid grains is reviewed briefly. The various proposals for formation of cometary nuclei are described and commented upon. With three exceptions, all hypotheses conclude or imply that a single compact object forms. It has been almost universally assumed that grain accretion produced compact aggregates as is the case with liquid drops, and that this process continued. Several hypotheses start with Goldreich-Ward-type gravitational instabilities. The collapse for this case also occurs at low velocities in the cm-s -1 to ms _ 1 range. Experiment and theory show that under these conditions, low-density, filamentary clusters form that are fractal aggregates with a fractal dimension approximately equal to two. Agglomeration of these clusters produces larger, compressible planetesimals or cometesimals, which efficiently combine upon colliding. In order to form cometary nuclei, the initial temperature must be about 50 K and not undergo a significant temperature rise during the accumulation process. The collision process can be analyzed with some simplifying assumptions using the limited experimental data available for the compaction of low-density powders. The calculations show that accumulation will occur at low temperatures. For a more refined analysis, experiments to study impacts on low-density powders are required. Models of cometary nuclei are reviewed, and a simple model of the structure that results from the accumulation of fluffy aggregates is described.1 .

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Section: Impact Velocities Of Grainssupporting

confidence: 63%

Section: 3 Accumulation Of Fluffy Aggregatesmentioning

confidence: 91%

Section: 3 Accumulation Of Fluffy Aggregatesmentioning

confidence: 96%

Section: Accumulation From Solid Grainsmentioning

confidence: 99%

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The Accumulation and Structure of Comets

Donn¹

1989

International Astronomical Union Colloquium

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“…These extrasolar planetary systems may correspond to the planetary systems formed in significantly massive disks. The other disks with smaller masses, which are the majority of the disks, may form Earth-like planets, if planetary formation is not inhibited by other processes such as inhibition of planetesimal formation due to turbulence in a disk (e.g., Weidenschilling 1984) or rapid planet migration (type I migration) induced by tidal interactions with a disk (Ward 1986(Ward , 1997.…”

Section: Diversity Of Planetary Systemsmentioning

confidence: 99%

Terrestrial Planet Formation: The Solar System and Other Systems

Ida¹,

Kokubo²

2004

Symp. - Int. Astron. Union

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Abstract.Accretion of terrestrial planets and solid cores of jovian planets is discussed, based on the results of our N-body simulations. Protoplanets accrete from planetesimals through runaway and oligarchic growth until they become isolated. The isolation mass of protoplanets in terrestrial planet region is about 0.2 Earth mass, which suggests that in the final stage of terrestrial planet formation giant impacts between the protoplanets occur. On the other hand, the isolation mass in jovian planet region is about a few to 10 Earth masses, which may be massive enough to form a gas giant. Extending the above arguments to disks with various initial masses, we discuss diversity of planetary systems. We predict that the extrasolar planets so far discovered may correspond to the systems formed from disks with large initial masses and that the other disks with smaller masses, which are the majority of the disks, may form Earth-like planets.

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Formation of Terrestrial Planets

Raymond

2010

Formation and Evolution of Exoplanets

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Evolution of grains in a turbulent solar nebula

Cited by 223 publications

References 18 publications

The Accumulation and Structure of Comets

The Accumulation and Structure of Comets

Terrestrial Planet Formation: The Solar System and Other Systems

Formation of Terrestrial Planets

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