Water transport from collapsing prestellar cores to forming disks: evolution of the HDO/H2O ratio

We investigate the transport of H2O and HDO ices from the collapse of rotating cores to the formation of disks. We adopt a two-dimensional physical model in order to trace fluid parcels, in which molecular evolution is simulated using a gas-ice chemical model. We find that water ice accreting from the protostellar envelope onto the disks can have a variation of the HDO/H2O ratio, reproducing the variation of the HDO/H2O ratio observed in comets. The result suggests that processing of water in the disk itself is not necessarily required to account for the variation of the HDO/H2O ratio in comets.