Heating and evaporation of Icy particles in the vicinity of comets

Lichtenegger, Herbert; Kömle, Norbert I.

doi:10.1016/0019-1035(91)90110-f

Cited by 37 publications

(25 citation statements)

References 15 publications

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“…Modelling of water sublimation from grains by previous investigators (Liechtenegger & Kömle 1990) has demonstrated how the grains are eroded, not at a steady rate, but with a very quick sublimation "burst" at the end of the grain lifetime. Their model was run for r h = 1 AU, and treated solid grains of pure water ice, sublimating from the surface.…”

Section: Modelingmentioning

confidence: 98%

Icy grains as a source of CO in comet 29P/Schwassmann-Wachmann 1

Gunnarsson

2003

A&A

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Abstract.A model of micron-sized icy grains is used to simulate the behaviour of solid material ejected from comet 29P/Schwassmann-Wachmann 1, which resides at ∼6 AU from the Sun. It is demonstrated that a population of grains composed primarily of water ice can release their ice content on timescales of order 10 6 s. This justifies the idea that icy grains can serve as an extended source of more volatile species, as was assumed when evidence for a coma source of CO was found in radio observations of this comet. The model also predicts short lifetimes for the icy grains inside 3 AU from the Sun, removing the extended appearance of the CO production at smaller heliocentric distances, as seen in comet Hale-Bopp. A grain population sublimating in a time interval similar to that derived for the coma source of CO in comet 29P/Schwassmann-Wachmann 1 must have most of its mass concentrated to small (with radii <5 µm) or porous grains. Those grains must carry a significant ice content, with an refractory to ice ratio of less than ∼30%. By introducing continuous grain fragmentation the extended source activity can be reproduced for a grain population that includes larger particles. This would call for grains to split into smaller pieces on a timescale of ∼5 × 10 5 s.

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Section: Modelingmentioning

confidence: 98%

Icy grains as a source of CO in comet 29P/Schwassmann-Wachmann 1

Gunnarsson

2003

A&A

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“…where p v,ice is the vapour pressure of ice, calculated from an approximation formula of Lichtenegger & Kömle (1991). The steam pressure p H2O is calculated as in Paper I.…”

Section: The Opacitymentioning

confidence: 99%

Radial mixing in protoplanetary accretion disks

Wehrstedt¹,

Gail²

2002

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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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“…where m H 2 O is the mass of the water molecule, k B is the Boltzmann constant and P v is the vapor pressure derived from Lichtenegger & Komle (1991):…”

Section: Model Of the Sublimation Of Icy Grainsmentioning

confidence: 99%

Investigation of dust and water ice in comet 9P/Tempel 1 fromSpitzerobservations of the Deep Impact event

Gicquel

Bockelée‐Morvan

Захаров

et al. 2012

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Context. The Spitzer spacecraft monitored the Deep Impact event on 2005 July 4 providing unique infrared spectrophotometric data that enabled exploration of comet 9P/Tempel 1's activity and coma properties prior to and after the collision of the impactor. Aims. The time series of spectra take with the Spitzer Infrared Spectrograph (IRS) show fluorescence emission of the H 2 O ν 2 band at 6.4 μm superimposed on the dust thermal continuum. These data provide constraints on the properties of the dust ejecta cloud (dust size distribution, velocity, and mass), as well as on the water component (origin and mass). Our goal is to determine the dust-to-ice ratio of the material ejected from the impact site. Methods. The temporal evolution of the continuum was analyzed using a dust thermal model which considers amorphous carbon and intimate silicate-carbon mixtures. The water emission was extracted from the spectra and the water columns within the Spitzer extraction aperture were inferred using a fluorescence excitation model. Time-dependent models simulating the development of the ejecta cloud and the sublimation of icy grains were developed to interpret the temporal evolution of both dust and water emissions within the field of view. Results. Both the color temperature of the grains in the ejecta cloud (375 ± 5 K) and their size distribution show that a large quantity of submicron grains were ejected by the impact. The velocity of the smallest grains is 230 m s −1 , with a power index for the size dependence of 0.3−0.5, in agreement with gas loading. The total mass of dust is (0.7−1.2) × 10 5 kg for grain sizes 0.1−1 μm and (0.5−2.1) × 10 6 kg for sizes 0.1−100 μm. A sustained production of water is observed, which can be explained by the sublimation of pure ice grains with sizes less than 1 μm and comprising a mass of ice of (0.8−1.8) × 10 7 kg. The contribution of dirty ice grains to the ice budget is negligible. Assuming that water was essentially produced by icy grains present in the ejecta cloud, our measurements suggest a very high ice-to-dust ratio of about 10 in the excavated material, which greatly exceeds the gas-to-dust production rate ratio of ∼0.5 measured for the background coma. Alternately, if a large amount of material felt back to the surface and sublimated, ice-to-dust ratios of 1−3 are not excluded. A better understanding of the cratering event on 9P/Tempel 1 is required to disentangle between the two hypotheses. Evidence for grain fragmentation in the ejecta cloud is found in the data. The pre-impact water production rate is measured to be (4.7 ± 0.7) × 10 27 mol s −1 .

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Heating and evaporation of Icy particles in the vicinity of comets

Cited by 37 publications

References 15 publications

Icy grains as a source of CO in comet 29P/Schwassmann-Wachmann 1

Icy grains as a source of CO in comet 29P/Schwassmann-Wachmann 1

Radial mixing in protoplanetary accretion disks

Investigation of dust and water ice in comet 9P/Tempel 1 fromSpitzerobservations of the Deep Impact event

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