Interstellar Dust Between Light and Darkness

Space dust is an integral element of interstellar medium, along with interstellar duct and various fields. To understand the space phenomena, the astronomers need to know the properties of dust particles, since we observe any object in the Universe through this dusty curtain. The nuclei of dust particles, consisting of carbon and silicon compounds, are covered with icy mantles made of frozen water and other molecules. One can determine the composition of the mantles and high-melting silicon nuclei using observational methods of Earth-bound astronomy. But it is much harder to study the composition of carbon nuclei, since one can observe their emissions only for a limited class of objects. These can be observed in photodissociation regions in midand far-IR range, which is mostly inaccessible from the Earth. The photodissociation regions (PDRs) are regions in space, transitional between ionized hydrogen and molecular gas. Planning of every extraterrestrial infrared observatory goes along with intense theoretical studies of carbon space dust. The modeling of PDRs, studies of microphysics in the dust evolution in PDRs, observations of PDRs with Russian and foreign telescopes are run in the Institute of Astronomy of the Russian Academy of Sciences.

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