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Giovanni Strazzulla Mario Garozzo Oscar Gomis 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2009
We present experimental results in order to understand the physico-chemical effects induced by fast ions irradiating sulfur bearing molecules. The experiments are relevant both to Solar System objects (icy satellites, comets, TNOs) and icy mantles on grains in the interstellar medium. Here we concentrate on the application to the Galilean moons that are exposed to high energetic particle fluxes in the jovian magnetosphere. 相似文献
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Surface temperature and the available effective energy strongly influence the mass flux of H2O and minor volatiles from the nucleus. We perform computer simulations to model the gas flux from volatile, icy components
in porous ice-dust surfaces, in order to better understand results from observations of comets. Our model assumes a porous
body containing dust, one major ice component (H2O) and up to eight minor components of higher volatility (e.g. CO, CH4, CH3OH, HCN, C2H2, H2S), The body's porous structure is modeled as a bundle of tubes with a given tortuosity and an initially constant pore diameter.
Heat is conducted by the matrix and carried by the vapors. The model includes radially inward and outward flowing vapor within
the body, escape of outward flowing gas from the body, complete depletion of less volatile ices in outer layers, and recondensation
of vapor in deeper, cooler layers. From the calculations we obtain temperature profiles and changes in relative chemical abundances,
porosity and pore size distribution as a function of depth, and the gas flux into the interior and into the atmosphere for
each of the volatiles at various positions of the body in its orbit.
In this paper we relate the observed relative molecular abundances in the coma of Comet C/1995 O1 (Hale-Bopp) and of Comet
46P/Wirtanen to molecular fluxes at the surface calculated from our model.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
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M. Nuevo S.N. Milam S.A. Sandford B.T. De Gregorio G.D. Cody A.L.D. Kilcoyne 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2011
Organic residues formed in the laboratory from the ultraviolet (UV) photo-irradiation or ion bombardment of astrophysical ice analogs have been extensively studied for the last 15 years with a broad suite of techniques, including infrared (IR) and UV spectroscopies, as well as mass spectrometry. Analyses of these materials show that they consist of complex mixtures of organic compounds stable at room temperature, mostly soluble, that have not been fully characterized. However, the hydrolysis products of these residues have been partly identified using chromatography techniques, which indicate that they contain molecular precursors of prebiotic interest such as amino acids, nitrile-bearing compounds, and amphiphilic compounds. In this study, we present the first X-ray absorption near-edge structure (XANES) spectroscopy measurements of three organic residues made from the UV irradiation of ices having different starting compositions. XANES spectra confirm the presence of different chemical functions in these residues, and indicate that they are rich in nitrogen- and oxygen-bearing species. These data can be compared with XANES measurements of extraterrestrial materials. Finally, this study also shows how soft X rays can alter the chemical composition of samples. 相似文献
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