Sigurd Sigersen Jensen
Max-Planck-Institut für extraterrestrische Physik
Water deuteration toward embedded low-mass protostars: A physical and chemical diagnostic of the earliest stages of star formation
Understanding the evolution of water during star formation, from the molecular cloud down to the protoplanetary disk, is a central goal of astrochemistry. Open questions on this topic include when and where water is formed and how the water content is influenced by the local environment in which the protostar is formed. The formation of water and its deuterated isotopologues, such as HDO, depends strongly on the physical conditions, i.e. temperature and density, in the protostars natal environment. The D/H ratio is thus a powerful tracer for both the physical and chemical evolution of water during the star formation process. I will present ALMA observations of the HDO/H2O and D2O/HDO ratios toward isolated cores harboring young Class 0 protostars. The derived D/H ratios of water show strong evidence of chemical inheritance during the earliest stages of star formation. These results are further supported by new physio-chemical models of water deuteration during star formation in a 3D MHD simulation of a molecular cloud. The next step toward a complete understanding of the water trail from cloud to planet is to determine the D/H ratio of water during planet formation. For this task, SOFIA plays a critical role, allowing observations of the D/H ratio of water in comets and, potentially, in protoplanetary disks. Observations of water during the epoch of planet formation are vital for our understanding of volatile delivery in young planetary systems, including the origin of Earth’s water.