The NH2D/NH3ratio toward pre-protostellar cores around the UCHii region in IRAS 20293+3952

Context. The deuterium fractionation, , has been proposed as an evolutionary indicator in pre-protostellar and protostellar cores of low-mass star-forming regions.Aims. We investigate , with high angular resolution, in the cluster environment surrounding the UC region IRAS 20293+3952.Methods. We performed high angular resolution observations with the IRAM Plateau de Bure Interferometer (PdBI) of the ortho-NH2D 111–101 line at 85.926 GHz and compared them with previously reported VLA NH3 data.Results. We detected strong NH2D emission toward the pre-protostellar cores identified in NH3 and dust emission, all located in the vicinity of the UC region IRAS 20293+3952. We found high values of 0.1–0.8 in all the pre-protostellar cores and low values, < 0.1, associated with young stellar objects.Conclusions. The high values of in pre-protostellar cores could be indicative of evolution, although outflow interactions and UV radiation could also play a role.