Deuterium enrichment of the interstellar medium |
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| Institution: | 1. Indian Centre For Space Physics, 43 Chalantika, Garia Station Road, Kolkata 700084, India;2. S.N. Bose National Center for Basic Sciences, JD-Block, Salt Lake, Kolkata 700098, India;1. Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008, China;2. School of Astronomy & Space Science, Nanjing University, Nanjing 210093, China;3. Key Laboratory of Modern Astronomy and Astrophysics, Nanjing University, Ministry of Education, Nanjing 210093, China;1. Department of Physics, Ben-Gurion University, Beer-Sheva 84105, Israel;2. Department of Physics, National Tsing-Hua University, Hsin-Chu 30013, Taiwan;3. Laboratoire d’Astrophysique de Marseille, Université de Provence, Marseille Cedex 13, France;1. Astronomy Department, National Research Institute of Astronomy and Geophysics, 11421 Helwan, Cairo, Egypt;2. Physics Department, College of Science, Northern Border University, 1321 Arar, Saudi Arabia;3. 1393 Garvin Street, Prince George, BC V2M 3Z1, Canada;1. V.P. & R.P.T.P. Science College, VallabhVidyanagar 388120, Gujarat, India;2. P.S. Science College, Kadi 382715, Gujarat, India |
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| Abstract: | Despite the low elemental abundance of atomic deuterium in the interstellar medium (ISM), observational evidence suggests that several species, both in the gas phase and in ices, could be heavily fractionated. We explore various aspects of deuterium enrichment by constructing a chemical evolution model in both gaseous and granular phases. Depending on various physical parameters, gases and grains are allowed to interact with each other through the exchange of their chemical species. It is known that HCO+ and N2H+ are two abundant gas phase ions in the ISM and, their deuterium fractionation is generally used to predict the degree of ionization in the various regions of a molecular cloud. For a more accurate estimation, we consider the density profile of a collapsing cloud. The radial distributions of important interstellar molecules, along with their deuterated isotopomers, are presented. Quantum chemical simulations are computed to study the effects of isotopic substitution on the spectral properties of these interstellar species. We calculate the vibrational (harmonic) frequencies of the most important deuterated species (neutral and ions). The rotational and distortional constants of these molecules are also computed in order to predict the rotational transitions of these species. We compare vibrational (harmonic) and rotational transitions as computed by us with existing experimental and theoretical results. It is hope that our results will assist observers in detecting several hitherto unobserved deuterated species. |
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| Keywords: | Astrochemistry Spectra ISM: molecules ISM: abundances |
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