Abstract

Water is abundant in the solid phase prior to star formation as revealed by ice absorption studies of embedded protostars. In contrast, water toward Class II disks is significantly depleted. Since planets are formed in those disks, it is crucial to understand how it is being transported there from the large-scale envelope around protostars. Class I protostellar systems have been shown to host well-defined Keplerian disks on similar scales to that of Class II systems. Disks around Class I sources thereby provide an interesting link to trace the water evolution. We here present non-detections of spatially resolved warm water lines toward four Class I protostars from the IRAM NOEMA and ALMA . The stringent upper limits suggest that the chemical processing of water due to grain growth and photodissociation are known to take place in Class II disks, already start during the earlier embedded phases. Deeper water line observations are required to further constrain the dependence of the water vapor abundance on the physical structure of the Class I disks.