Deuterated species are unique and powerful tools in astronomy since deuterium-to-hydrogen (D/H) enrichment in molecular species provides clues about their original environment of formation, chemistry, and the ionization level of the medium. But study of the deuterium chemistry is a challenging task because of the limited number of accurately determined rate coefficients and the sheer number of hydrogen dominated reactions in astrochemical networks. In this talk, I will present a state-of-the-art deuterium fractionation model which includes ortho/para chemistry of major protonated species. I will try to highlight the following key topics: (1) How observing few selected deuterated species can be a very effective tool to characterize cold and dark media where most molecules are depleted? (2) Does spin chemistry changes the deuterium enrichment of the interstellar medium? (3) Prediction for future observations for deuterated species in dense cores and protoplanetary disks. (4) Possible shortcomings of the model that could be addressed by theoretical quantum chemical calculations/experiments. References: 1. L. Majumdar, P. Gratier, M. Ruaud, V. Wakelam, C. Vastel, O. Sipila, F. Hersant, A. Dutrey, S. Guiolloteau, 2017, Chemistry of TMC-1 with multiply deuterated species and spin chemistry of H2, H2+, H3+ and their isotopologues, Monthly Notices of the Royal Astronomical Society, 466, 4470. 2. L. Majumdar, P. Gratier, I. Andron, V. Wakelam, E. Caux, 2017, A study of singly deuterated cyclopropenylidene c-C3HD in protostar IRAS 16293-2422, Monthly Notices of the Royal Astronomical Society, 467, 3525 3. L. Majumdar, V. Wakelam, C. Vastel, P. Gratier, M. Ruaud, , K. Willacy, A. Dutrey, S. Guiolloteau, Xavier Michaut, Francois Dulieu, 2017, A Three phase deuterium fractionation model with important laboratory processes on the grain surface, ApJ, 2017 (In Prep.) 4. L. Majumdar, V. Wakelam, A. Dutrey, K. Willacy, S. Guiolloteau, 2017, A Three phase deuterium fractionation model for protoplanetary disks, ApJ, 2017 (In Prep.)

Deuterium fractionation from molecular clouds to protoplanetary disks: Modeling and observation

255th National Meeting (2018)

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