Evolving Optical Properties of Annealing Silicate Grains: From Amorphous Condensate to Crystalline Mineral

Hallenbeck, Susan L.; Nuth, Joseph A.; Nelson, R. N.

doi:10.1086/308810

Cited by 102 publications

(123 citation statements)

References 12 publications

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“…As a result the characteritic timescale of annealing has a different form as compared to (7), and the annealing temperature increases from about 800 K to about 950 K in the present disk models. Though we did no time dependent model calculation with the law for the characteritic timescale of annealing of Hallenbeck et al (2000), we conclude that the disk structure would be somewhat influenced in the sense that the annealing zone is slightly shifted inwards, but it does not dependent critically on the annealing model.…”

Section: Dust Behaviour In the Diskmentioning

confidence: 76%

“…In an annealing experiment (Hallenbeck et al 1998;Hallenbeck et al 2000) there has been observed a different evolutionary track of annealing of magnesium silicates as compared to the experiments of Fabian et al (2000) and of Nuth & Donn (1982). Hallenbeck et al 1998 detect a stall phase within the annealing process, during which the spectral features of the silicates at 10 µm hardly change.…”

Section: Dust Behaviour In the Diskmentioning

confidence: 92%

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Radial mixing in protoplanetary accretion disks

Wehrstedt¹,

Gail²

2002

A&A

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Abstract. This work investigates the annealing of silicate dust, the combustion of carbon dust and radial mixing of both dust species within protoplanetary disks. For this purpose the diffusion-transport-reaction equations of both dust species (including annealing of silicate and carbon combustion) are simultaneously solved with the equations for the global evolution of an α-disk within an one-zone, time-dependent numerical model. The protostar-disk system is assumed to be in a quiescent stage which corresponds with the class II phase of evolution of stardisk systems. The results suggest that the diffusive transport spreads the dust globally throughout the disk, and therefore provides an explanation for the existence of crystalline silicate and methane within the primordial bodies of the solar system.

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Section: Dust Behaviour In the Diskmentioning

confidence: 76%

Section: Dust Behaviour In the Diskmentioning

confidence: 92%

Radial mixing in protoplanetary accretion disks

Wehrstedt¹,

Gail²

2002

A&A

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“…However, a major problem with the results of this study is that the IR spectrum of the warmed silicate residue does not resemble typical IR spectra observed for silicates in the ISM. Based on previous laboratory work, Hallenbeck et al ( , 2000 showed that the thermal annealing (T ≥ 1000 K) of a highly amorphous silicate condensate resulted in more ordered material with an IR spectrum displaying narrower peaks and absorption features that more closely resemble typical ISM silicate spectra. However, no natural process has been identified that would heat grains to temperatures significantly in excess of 1000 K in the ISM for sufficiently long time periods to reproduce the observed silicate spectral profile.…”

Section: In the Interstellar Mediummentioning

confidence: 99%

Dust destruction in the ISM: a re-evaluation of dust lifetimes

Jones

Nuth

2011

A&A

206

224

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Context. There is a long-standing conundrum in interstellar dust studies relating to the discrepancy between the time-scales for dust formation from evolved stars and the apparently more rapid destruction in supernova-generated shock waves. Aims. We re-examine some of the key issues relating to dust evolution and processing in the interstellar medium. Methods. We use recent and new constraints from observations, experiments, modelling and theory to re-evaluate dust formation in the interstellar medium (ISM). Results. We find that the discrepancy between the dust formation and destruction time-scales may not be as significant as has previously been assumed because of the very large uncertainties involved. Conclusions. The derived silicate dust lifetime could be compatible with its injection time-scale, given the inherent uncertainties in the dust lifetime calculation. The apparent need to re-form significant quantities of silicate dust in the tenuous interstellar medium may therefore not be a strong requirement. Carbonaceous matter, on the other hand, appears to be rapidly recycled in the ISM and, in contrast to silicates, there are viable mechanisms for its re-formation in the ISM.

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“…Alternatively, we can say that the silicate evolution index of Hallenbeck et al (2000) reached values greater than about 10 after 5 min. This corresponds to annealing temperatures of >1080 K in their experiments.…”

Section: Dust Absorption At Later Timesmentioning

confidence: 99%

Meteosat observation of the atmospheric entry of 2008 TC$\mathsf{_{3}}$ over Sudan and the associated dust cloud

Borovička¹,

Charvát²

2009

A&A

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We analyzed serendipitous observations by the Meteosat 8 weather satellite of the fireball caused by the entry of the small asteroid (or large meteoroid) 2008 TC 3 over northern Sudan on October 7, 2008. Meteosat 8 scans the Earth in 5 min cycles. The fireball was captured in the 2:45 UT images in four visible-near infrared channels (0.6-1.6 μm) at a height of 45 km, and in eight mid infrared channels (3.9-13.4 μm) at a height of 33 km. The latter channels also detected at least two dust clouds deposited in the atmosphere at the heights of about 44 and 36 km. The dust deposition was a result of severe atmospheric fragmentation of the asteroid, accompanied by fireball flares, which could be detected in the light scattered by the Earth's surface. The fireball brightness was measured at two random heights, 45 and 37.5 km, where it reached −18.8 and −19.7 mag, respectively. The peak brightness was probably higher than −20 mag. The color temperature of the fireball at 45 km was 3650 ± 100 K. Infrared spectra of the fresh dust clouds were dominated by the 10 μm Si-O band caused by recondensed amorphous silicates. Five minutes later, the dust clouds were detected in absorption of thermal radiation of the Earth. At that time, the silicates were largely crystalline, suggesting silicate smoke temperatures exceeding 1000 K. The total mass of the silicate smoke was estimated to be 3100 ± 600 kg. More mass was probably contained in larger, micron sized, and colder dust particles resulting from incomplete sublimation of the asteroidal material and detected later by Meteosat 8 and 9 in scattered sunlight. Based on the heights of asteroid fragmentations, we guess that the bulk porosity of 2008 TC 3 was of the order of 50%, i.e. higher than the porosity of the recovered meteorite Almahata Sitta.

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Evolving Optical Properties of Annealing Silicate Grains: From Amorphous Condensate to Crystalline Mineral

Cited by 102 publications

References 12 publications

Radial mixing in protoplanetary accretion disks

Radial mixing in protoplanetary accretion disks

Dust destruction in the ISM: a re-evaluation of dust lifetimes

Meteosat observation of the atmospheric entry of 2008 TC$\mathsf{_{3}}$ over Sudan and the associated dust cloud

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