Variations of the HCO+, HCN, HNC, N2H+, and NH3 Deuterium Fractionation in High-Mass Star-Forming Regions

We use spectra and maps of the J = 1 - 0 and J = 2 - 1 DCO+, DCN, DNC, lines, and 1(11)-1(01) ortho- and para-NH2D lines, obtained with the Institut de Radioastronomie Millimetrique (IRAM)-30m telescope, as well as observations of their hydrogenated isotopologues to study deuteration processes in five high-mass star-forming regions. The temperature was estimated from CH 3CCH lines, also observed with theIRAM-30m telescope, and from NH (3) lines, observed with the 100 m radio telescope in Effelsberg, as well as using the integrated intensity ratios of the J = 1 - 0 (HCN)-C-13 and (HNC)-C-13 lines and their main isotopologues. Applying a non-local thermodynamic equilibrium radiative transfer model with radex, the gas density and the molecular column densities were estimated. D/H ratios are 0.001-0.05 for DCO+, 0.001-0.02 for DCN, 0.001-0.05 for DNC, and 0.02-0.4 for NH2D. The D/H ratios decrease with increasing temperature in the range of 20-40 K and slightly vary at densities cm(-3). The deuterium fraction of is 0.008-0.1 at temperatures in the range of 20-25 K and at a density of similar to 10(5) cm(-3). We also estimate relative abundances and find similar to 10(-11)-10(-9) for DCO+ and DNC, similar to 10(-11)-10(-10) for , and similar to 10(-10)-10(-8) for NH2D. The relative abundances of these species decrease with increasing temperature. However, the DCN/H-2 ratio is almost constant (similar to 10(-10)). The observational results agree with the predictions of chemical models (although in some cases there are significant differences).