On the Average Chemical Composition of Cometary Dust

Jeßberger, E. K.; Kissel, J.; Fechtig, H.; Krueger, F. R.

doi:10.1007/978-3-642-72640-8_3

Cited by 13 publications

(9 citation statements)

References 21 publications

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“…As is known from spacecraft missions to Comet Halley, the mineral part of comet material, or dust, which includes iridium, is close, in its chemical composition, to carbonaceous chondrites CI but contains about 10 times more carbon and nitrogen relative to these (Jessberger et al, 1986;Jessberger and Kissel, 1991). We concluded that the isotopic effects in the peat could be attributed to the conservation in the peat of comet core material with a low mineral dust fraction.…”

Section: Carbonmentioning

confidence: 73%

Isotopic–geochemical study of nitrogen and carbon in peat from the Tunguska Cosmic Body explosion site

Kolesnikov

Longo

Boettger

et al. 2003

Icarus

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Isotopic-geochemical investigations were carried out on peat samples from the 1908 Tunguska Cosmic Body (TCB) explosion area. We analyzed two peat columns from the Northern peat bog, sampled in 1998, and from the Raketka peat bog, sampled during the 1999 Italian expedition, both located near the epicenter of the TCB explosion area. At the depth of the "catastrophic" layer, formed in 1908, and deeper, one can observe shifts in the isotopic composition of nitrogen (up to ⌬ 15 N ϭ ϩ7.2‰) and carbon (up to ⌬ 13 C ϭ ϩ2‰) and also an increase in the nitrogen concentration compared to those in the normal, upper layers, unaffected by the Tunguska event. One possible explanation for these effects could be the presence of nitrogen and carbon from TCB material and from acid rains, following the TCB explosion, in the "catastrophic" and "precatastrophic" layers of peat. We found that the highest quantity of isotopically heavy nitrogen fell near the explosion epicenter and along the TCB trajectory. It is calculated that 200,000 tons of nitrogen fell over the area of devastated forest, i.e., only about 30% of the value calculated by Rasmussen et al. (1984). This discrepancy is probably caused by part of the nitrogen having dispersed in the Earth's atmosphere. The isotopic effects observed in the peat agree with the results of previous investigations (Kolesnikov et al., 1998a(Kolesnikov et al., , 1998bRasmussen et al., 1999) and also with the increased content of iridium and other platinoids found in the corresponding peat layers of other columns (Hou et al., 1998(Hou et al., , 2000. These data favor the hypothesis of a cosmochemical origin of the isotopic effects.

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Section: Carbonmentioning

confidence: 73%

Isotopic–geochemical study of nitrogen and carbon in peat from the Tunguska Cosmic Body explosion site

Kolesnikov

Longo

Boettger

et al. 2003

Icarus

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“…Neutral oxygen (O i) and CO, which are not listed in the table of Lagrange et al (1998) have even smaller β values, as their main spectral lines do not fall in spectral ranges where the flux of β Pic is important. In standard models or cometary dust composition (see e.g Jeßberger et al 1987Jeßberger et al , 1991, these species are fairly abundant with respect to other ones. Note that circumstellar components of C i and CO have been observed in the spectrum of β Pic (Vidal-Madjar et al 1994), showing that these species are actually present.…”

Section: Consequence For the Feb Evaporation Modelmentioning

confidence: 99%

The physico-chemical history of Falling Evaporating Bodies aroundβPictoris: investigating the presence of volatiles

Karmann

Beust

Klinger

2001

A&A

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Abstract. Transient spectral absorption events have been monitored for many years toward the star β Pictoris and have been interpreted as resulting from the transit across the line of sight of evaporating comet-sized bodies (Falling Evaporating Bodies, or FEBs). The model shows that these bodies come from circular orbits at > ∼ 4 AU, becoming star-grazers due to planetary perturbations. The physics of the evaporation of those bodies is widely influenced by their physico-chemical properties, especially the presence of volatile matter. We investigate here this question from a modeling point of view, adapting for that case the models designed for solar comets. We simulate the physico-chemical evolution of the FEB progenitors on circular orbits for a time comparable to the supposed age of β Pic, and constrain the quantity of volatiles present in them in relationship with its age and to the semi-major axis of the orbits. We also constrain this semi-major axis by investigating its influence on the dynamical model of FEB generation by planetary perturbations, and show that it is probably less than ∼10 AU. Finally, we show that demanding the FEB progenitors to be icy in a major part of their volume at those distances is probably an unrealistic constraint, and that they more likely look like asteroids with perhaps a small icy nucleus rather than fully icy comets. This result leads to a revision of the FEB evaporation model that has been assumed up to now.

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“…Rock and CHON do not occur as pure components but are intimately mixed down to the finest scale (Lawler & Brownlee 1992). The CHON component is mainly organic refractory material (Jessberger et al 1986;Kissel & Krueger 1987). The Rock component is mainly composed of Mg-rich, Fe-poor silicates (Jessberger 1999).…”

Section: The Compositionmentioning

confidence: 99%

Modeling of the light scattering properties of cometary dust using fractal aggregates

Bertini

Thomas

Barbieri

2006

A&A

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Aims. The nature of cometary dust is still elusive. In order to constrain the physical properties of dust in cometary coma, we modeled the observed scattering parameters, investigating different morphological and compositional effects. Methods. We used fractal aggregates as dust particles. The scattering behavior of extremely elongated dust particles, similar to those formed in micro-gravity aggregation experiments and more compact aggregates, have been studied with the discrete-dipole approximation theory. Results. Results show that particles comparable in size to the incident wavelength provide the best qualitative fits. A silicate composition gives a good fit to the polarization and the phase function, but is characterized by large albedo. Organic and mixed compositions provide low albedos but do not fit the polarization and phase function curves well. Compact particles seem to reproduce the observed parameters better, indicating a possible morphological metamorphism of dust since the time of formation. The observed different polarization classes may be explained in terms of different monomer sizes, if a cluster of spheres models are used.

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On the Average Chemical Composition of Cometary Dust

Cited by 13 publications

References 21 publications

Isotopic–geochemical study of nitrogen and carbon in peat from the Tunguska Cosmic Body explosion site

Isotopic–geochemical study of nitrogen and carbon in peat from the Tunguska Cosmic Body explosion site

The physico-chemical history of Falling Evaporating Bodies aroundβPictoris: investigating the presence of volatiles

Modeling of the light scattering properties of cometary dust using fractal aggregates

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