Deuterium fractionation in warm dense interstellar clumps

摘要: Aims.In a recently published 1-millimeter line survey of the Orion Bar by Leurini et al., confirmation dense neutral clumps was reported based mainly on an analysis methanol spectral lines. Within these clumps, high abundance ratio found between deuterated isotopologue DCN and HCN. Methods.In this paper, we use steady-state chemical modelling to determine if DCN/HCN can be understood in terms gas-phase processes. Results.Our results show that, at temperatures (50-75 K) densities ( 5 - 20 x 10{6} cm-3) vicinity those measured, calculated reach 0.01 or even higher, good agreement with measured range 0.007-0.009. Moreover, fractional HCN is also that reported. Other computed ratios normal isotopologues are for physical conditions clumps. The analyzed as functions temperature density simple formula. In general, somewhat dependent choice two very different sets elemental abundances, one which "standard" low-metal set, while other term "warm-core" set.