A high HDO/H2O ratio in the Class I protostar L1551 IRS5

Water molecules play a key role in the interstellar medium as they cool down the warm regions and boost the gravitational collapse leading to star formation. They are also very abundant and fundamental to the emergence of life. Water molecules have been detected at different stages of the star formation process from cold prestellar cores to protoplanetary disks. The deuteration of water, through both the HDO/H2O and D2O/HDO ratios, is a chemical tool used to characterize the formation of water and its evolution from the early stages of the star formation process up to its delivery to planets. Since then, most of the studies focused on Class 0 sources. Studies on more evolved sources are scarce but are needed to reconstruct the chemical evolution of water. We will present here results regarding the water deuteration of L1551 IRS5, a Class I solar-type protostar and FUor-like object observed with the NOEMA interferometer. Thanks to these interferometric data, the water deuteration can be investigated in the innermost regions of the protostar at scales of about a few 100 au which is similar to the sizes of disks in which planets form. The results will be compared to previous studies on protostars and comets.