Organic Molecules in the Icy Bodies of Planetary Systems -Accepted Notions and New Ideas (original) (raw)

2018, Open Astronomy

Cometary bodies are acknowledged to contain some of the most pristine matter in the Solar System, including ices and minerals. Certain number of previously unidentified spectral emission features detected in comets can be explained as emission by hydrocarbon molecules enclosed in a Shpolskii matrix and forming frozen hydrocarbon particles. UV-induced photoluminescence spectra of several self-organized molecules exhibit emission lines coincident with unidentified cometary lines, and open the possibility of the presence of this complex organic as components of the pristine organic inventory of comets. Complex organic was detected also in three satellites of Saturn. We describe in this paper results of our investigation of complex organic of the small bodies and present new approaches and hypotheses.

Organic component of cometary ice

Investigations of the luminescence of frozen hydrocarbon particles of icy cometary halo have been made. The process of luminescence of icy particles in shortwave-length solar radiation field is considered. The comparative analysis of observed and laboratory data leads of 72 lumi-nescent emission lines in the spectrum of 153P/Ikeya-Zhang comet. Several aspects of the problem are discussed.

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FROZEN HYDROCARBONS IN COMETS

Recent investigations of the luminescence of frozen hydrocarbon particles of icy cometary halos have been carried out. The process of luminescence of organic icy particles in a short-wavelength solar radiation field is considered. A comparative analysis of observed and laboratory data leads to 72 luminescent emission lines in the spectrum of the comet 153P/Ikeya-Zhang. The concept of cometary relict matter is presented, and the creation of a database of unidentified cometary emission lines is proposed.

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Unidentified Cometary Emission Lines as the Photoluminescence of Frozen Hydrocarbon Particles

—We discuss the possible nature of unidentified cometary emission lines. We propose a model of the ice particles in cometary halos as a mixture of frozen polycyclic aromatic hydrocarbons (PAHs) and acyclic hydrocarbons. We describe the general properties of frozen hydrocarbon particles (FHPs) and suggest interpreting some of the unidentified cometary emission lines as the photoluminescence of FHPs. We compare the positions of unidentified emission lines in the spectrum of Comet 122Р/de Vico with the positions of quasi-lines in the photoluminescence spectrum of PAHs that were dissolved in acyclic hydrocarbons at a temperature of 77 К and that constituted a polycrystalline solution. We estimate the detectability of FHP photoluminescence in cometary spectra. c 2004 MAIK " Nauka/Interperiodica " .

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