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

Kudo, Tatsuyuki; Kouchi, Akira; Arakawa, Masahiko; Nakano, Hideyuki

doi:10.1111/j.1945-5100.2002.tb01178.x

Cited by 24 publications

(46 citation statements)

References 21 publications

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“…To account for ice and organics present beyond the snow line we must recognize that the surface energy is significantly larger for these materials. The experiments by Kouchi et al (2002) and Kudo et al (2002) on organics and by Gundlach & Blum (2015) on water ice indeed show that both substances are significantly stickier than silica. It is thus reasonable to assume that the velocity range for growth as described above can be an order of magnitude higher, or 0.3 < ∼ v rel < ∼ 30 m s −1 (Wada et al 2009).…”

Section: Formation Of Cometesimalsmentioning

confidence: 75%

The primordial nucleus of comet 67P/Churyumov-Gerasimenko

Davidsson

Sierks

Güttler

et al. 2016

A&A

187

162

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Context. We investigate the formation and evolution of comet nuclei and other trans-Neptunian objects (TNOs) in the solar nebula and primordial disk prior to the giant planet orbit instability foreseen by the Nice model. Aims. Our goal is to determine whether most observed comet nuclei are primordial rubble-pile survivors that formed in the solar nebula and young primordial disk or collisional rubble piles formed later in the aftermath of catastrophic disruptions of larger parent bodies. We also propose a concurrent comet and TNO formation scenario that is consistent with observations. Methods. We used observations of comet 67P/Churyumov-Gerasimenko by the ESA Rosetta spacecraft, particularly by the OSIRIS camera system, combined with data from the NASA Stardust sample-return mission to comet 81P/Wild 2 and from meteoritics; we also used existing observations from ground or from spacecraft of irregular satellites of the giant planets, Centaurs, and TNOs. We performed modeling of thermophysics, hydrostatics, orbit evolution, and collision physics. Results. We find that thermal processing due to short-lived radionuclides, combined with collisional processing during accretion in the primordial disk, creates a population of medium-sized bodies that are comparably dense, compacted, strong, heavily depleted in supervolatiles like CO and CO 2 ; they contain little to no amorphous water ice, and have experienced extensive metasomatism and aqueous alteration due to liquid water. Irregular satellites Phoebe and Himalia are potential representatives of this population. Collisional rubble piles inherit these properties from their parents. Contrarily, comet nuclei have low density, high porosity, weak strength, are rich in supervolatiles, may contain amorphous water ice, and do not display convincing evidence of in situ metasomatism or aqueous alteration. We outline a comet formation scenario that starts in the solar nebula and ends in the primordial disk, that reproduces these observed properties, and additionally explains the presence of extensive layering on 67P/Churyumov-Gerasimenko (and on 9P/Tempel 1 observed by Deep Impact), its bi-lobed shape, the extremely slow growth of comet nuclei as evidenced by recent radiometric dating, and the low collision probability that allows primordial nuclei to survive the age of the solar system. Conclusions. We conclude that observed comet nuclei are primordial rubble piles, and not collisional rubble piles. We argue that TNOs formed as a result of streaming instabilities at sizes below ∼400 km and that ∼350 of these grew slowly in a low-mass primordial disk to the size of Triton, Pluto, and Eris, causing little viscous stirring during growth. We thus propose a dynamically cold primordial disk, which prevented mediumsized TNOs from breaking into collisional rubble piles and allowed the survival of primordial rubble-pile comets. We argue that comets formed by hierarchical agglomeration out of material that remained after TNO formation, and that this slow growth was a necessity...

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Section: Formation Of Cometesimalsmentioning

confidence: 75%

The primordial nucleus of comet 67P/Churyumov-Gerasimenko

Davidsson

Sierks

Güttler

et al. 2016

A&A

187

162

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“…The aggregates may be coated with a sticky organic material, observed on the surface of 67P's nucleus (Capaccioni et al 2015). This organic coating was observed on interplanetary dust particles collected in Earth's stratosphere (Flynn et al 2013); it can have a significantly higher tensile strength Kudo et al 2002) than is provided by van der Waals forces assumed in Equation (2). The GDS showers offer evidence of fragmentation of aggregates, suggesting that some junctions are not coated by organic material and are linked by van der Waals forces only.…”

Section: Particle Fragmentationmentioning

confidence: 98%

Density and Charge of Pristine Fluffy Particles From Comet 67p/Churyumov–gerasimenko

Fulle

Corte

Rotundi

et al. 2015

ApJ

140

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The Grain Impact Analyzer and Dust Accumulator (GIADA) instrument on board ESA's Rosetta mission is constraining the origin of the dust particles detected within the coma of comet 67 P/Churyumov-Gerasimenko (67P). The collected particles belong to two families: (i) compact particles (ranging in size from 0.03 to 1 mm), witnessing the presence of materials that underwent processing within the solar nebula and (ii) fluffy aggregates (ranging in size from 0.2 to 2.5 mm) of sub-micron grains that may be a record of a primitive component, probably linked to interstellar dust. The dynamics of the fluffy aggregates constrain their equivalent bulk density to <1 kg m −3 . These aggregates are charged, fragmented, and decelerated by the spacecraft negative potential and enter GIADA in showers of fragments at speeds <1 m s −1 . The density of such optically thick aggregates is consistent with the low bulk density of the nucleus. The mass contribution of the fluffy aggregates to the refractory component of the nucleus is negligible and their coma brightness contribution is less than 15%.

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“…Kudo et al (2002) measured the temperature dependence of viscoelastic properties of molecular-cloud organic analogues prepared by mixing chemical reagents (as described in Kouchi et al 2002), and concluded that the aggregation of dust coated with molecular-cloud organic matter would be promoted at 200-300 K. However, there have been no further studies of the viscoelastic properties of organic matter, especially organic matter synthesized under molecular cloud conditions.…”

Section: Introductionmentioning

confidence: 99%

“…These conditions might also reflect the irradiation of organic compounds in the outer solar nebula (Chiang & Goldreich 1997;Ciesla & Sandford 2012). The remaining residue is hereafter referred to as DCOR, for Diffuse Cloud Organic Residue Kudo et al 2002).…”

Section: Introductionmentioning

confidence: 99%

Evolution of Morphological and Physical Properties of Laboratory Interstellar Organic Residues with Ultraviolet Irradiation

Piani

Tachibana

Hama

et al. 2017

ApJ

Self Cite

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Refractory organic compounds formed in molecular clouds are among the building blocks of the solar system objects and could be the precursors of organic matter found in primitive meteorites and cometary materials. However, little is known about the evolutionary pathways of molecular cloud organics from dense molecular clouds to planetary systems. In this study, we focus on the evolution of the morphological and viscoelastic properties of molecular cloud refractory organic matter. We found that the organic residue, experimentally synthesized at ∼10 K from UV-irradiated H 2 O-CH 3 OH-NH 3 ice, changed significantly in terms of its nanometerto micrometer-scale morphology and viscoelastic properties after UV irradiation at room temperature. The dose of this irradiation was equivalent to that experienced after short residence in diffuse clouds (10 4 years) or irradiation in outer protoplanetary disks. The irradiated organic residues became highly porous and more rigid and formed amorphous nanospherules. These nanospherules are morphologically similar to organic nanoglobules observed in the least-altered chondrites, chondritic porous interplanetary dust particles, and cometary samples, suggesting that irradiation of refractory organics could be a possible formation pathway for such nanoglobules. The storage modulus (elasticity) of photo-irradiated organic residues is ∼100 MPa irrespective of vibrational frequency, a value that is lower than the storage moduli of minerals and ice. Dust grains coated with such irradiated organics would therefore stick together efficiently, but growth to larger grains might be suppressed due to an increase in aggregate brittleness caused by the strong connections between grains.

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

Cited by 24 publications

References 21 publications

The primordial nucleus of comet 67P/Churyumov-Gerasimenko

The primordial nucleus of comet 67P/Churyumov-Gerasimenko

Density and Charge of Pristine Fluffy Particles From Comet 67p/Churyumov–gerasimenko

Evolution of Morphological and Physical Properties of Laboratory Interstellar Organic Residues with Ultraviolet Irradiation

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