A study of singly deuterated cyclopropenylidene c-C3HD in the protostar IRAS 16293-2422

Cyclic-C3HD (c-C3HD) is a singly deuterated isotopologue of c-C3H2, which is one of the most abundant and widespread molecules in our Galaxy. We observed IRAS 16293-2422 in the 3-mm band with a single frequency set-up using the EMIR heterodyne 3 mm receiver of the IRAM 30-m telescope. We observed seven lines of c-C3HD and three lines of cC(3)H(2). Observed abundances are compared with astrochemical simulations using the NAUTILUS gas-grain chemical model. Assuming that the size of the protostellar envelope is 3000 au and assuming the same excitation temperatures for both c-C3H2 and c-C3HD, we obtain a deuterium fraction of 14(-3)(+4)per cent.