Comets matter

The astrochemistty of ions may be divided into topics of interstellar clouds, stellar atmospheres, planetary atmospheres and comets. There are many areas of astrophysics (stars, planetary nebulae, novae, supemovae) where highly ionized species are important, but beyond the scope of ion chemistry . (Still, molecules, including H2O, are observed in solar spectra [155] and a surprise in the study of Supernova 1987A was the identification of molecular species, CO, SiO and possibly ITf[156. 157]. ) In the early universe, after expansion had cooled matter to the point that molecules could fonn, the small fraction of positive and negative ions that remained was crucial to the fomiation of molecules, for example [156]... 

Except for the moon and the planet Mars, no extraterrestrial body has had pieces of its mass directly examined by scientists in an earthly laboratory. This means that there has been no laboratory sample preparation scheme performed on samples of solid matter from any of the other planets, their moons, comets, or asteroids. And yet we read repeatedly about how scientists have been able to surmise the... 

Figures. Comet assay is shown for human K562 cells exposed to an extract produced from particulate matter released from sample PM 5 filters, to an extract derived from an unloaded filter, or to hydrogen peroxide (100 pM) as a control. Cells with little or no DNA damage are labeled 1 and 2, and those with extensive damage are labeled 3 and 4.

Star formation and the formation of star systems with planets around them, constantly takes place in dense interstellar clouds. The material present in these clouds is incorporated into the objects that are formed during this process. Pristine or slightly altered organic matter from the cloud from which our solar-system was formed is therefore present in the most primitive objects in the solar system comets, asteroids, and outer solar-system satellites. Pieces of asteroids (and perhaps comets) can be investigated with regards to these components through the analyses of meteorites (and eventually in samples returned from these bodies by spacecraft) in laboratories on Earth. The infall of asteroid and comet material from space may have contributed to the inventory of organic compounds on primordial Earth. 

We have now set the stage for the next two chapters - anhydrous planetesimals and ice-bearing comets and asteroids. These objects contain the organic matter, noble gases, and sometimes ices that we have just learned about, and they provide us with the best record of primitive materials in the solar system. 

Gilmour, I. (2004) Structural and isotopic analysis of organic matter in carbonaceous chondrites. In Treatise on Geochemistry, Vol. 1. Meteorites, Comets, and Planets, ed. Davis, A. M. Oxford Elsevier, pp. 269-290. 

The organic matter in these comet grains has also been characterized (Sandford et al.,... 

Hydrogen in these particles is correlated with carbon and is presumed to occur in organic matter. Analyses of the isotopic composition of hydrogen (McKeegan et al., 2006) show D/H enrichments (Fig. 12.12). The D/H ratios overlap those of H20 in comets but are well below those determined for organic matter in CP IDPs. Measurements of nitrogen isotopes show 15N enhancements, suggesting an interstellar contribution. 

Measured D/H ratios in five bulk Stardust particles (black dots sizes represent relative particle sizes), and in micron-size subareas in one particle (open circles enclosed by oval) measured by ion microprobe. The particle compositions overlap D/H ratios in comets, IDPs, and the insoluble organic matter in chondrites. Modified from McKeegan et al. (2006). 

Kennicutt II, M.C., and Comet, P.A. (1992) research of sediment hydrocarbon sources multiparameter approaches. In Organic Matter Productivity, Accumulation, and Preservation in Recent and Ancient Sediments (Whelan, J.K., and Farrington, I.K., eds.), pp. 308-338, Columbia University Press, New York. 

FUMUS — is the Scoria, an incrustation on the floor, yet properly that which arises and brings the body with it. For there are two kinds of smoke, which mix with the earth, make the stars fall from heaven, make also comets and rainbows about the sun and moon. When the batia finds a mineral matter, then it is to the smallest extent mingled with it. It also becomes fixed and a metal, but should the batia not find any, then it becomes a mercury but the mineral power which it ought to find is clear sulphur washed, and partially fixed, and it is found in the extracted stones, and in sand. It shines like silver, and because nothing can be produced without this, it is found in every place... 

Cronin J. R., PizzareUo S., and Cruikshank D. P. (1988) Organic matter in carbonaceous chondrites, planetary satellites, asteroids and comets. In Meteorites and the Early Solar System (eds. J. F. Kerridge and M. S. Matthews). University of Arizona Press, Tucson, pp. 819-857. 

Strictly speaking, the title noble-gas chemistry should be an oxymoron. But the noble gases are not literally and completely noble in the sense that they fail entirely to interact chemically with other forms of matter. Under appropriate conditions in the laboratory they can form real compounds with other elements, although there is no evidence that actual noble-gas compounds are relevant in cosmochemistry (possibly excepting ice clathrates in comets). StiU, planetary materials do contain noble gases that were somehow incorporated into them, and at least some of these appear to have involved some form of chemical interaction. The issue of chemical interactions is a venerable topic in noble-gas cosmochemistry, but there are still questions that have been unanswered for a long time. 

Geiss J. (1988) Composition in Halley s comet clues to origin and history of commentary matter. Rev. Mod. Astron. 1, 1-27. 

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