Goddi, C.C.GoddiMOSCADELLI, LucaLucaMOSCADELLI2023-01-032023-01-032004http://hdl.handle.net/20.500.12386/32827We have conducted multi-epoch VLBI observations of the 22.2 GHz water masers towards three massive star forming regions (Sh 2-255 IR, WB89-234, AFGL 5142). For the maser fetures persistent in time, accurate values of the proper motions are derived. The comparison of the VLBI 22.2 GHz maps with the highest-resolution images of the sources Sh 2-255 IR and WB89-234 in several thermal tracers, may suggest that the water masers are most likely tracing the inner portion of the molecular outflows detected at much larger-scales. This interpretation is also confirmed by the results obtained by fitting to the data two different kinematical models, a Keplerian disk and a conical outflow. <P />Towards AFGL 5142 the water maser features are distributed in two different structures, whose axes are nearly perpendicular to each other. A possible interpretation is that the maser emission is tracing the disk/jet system nearby the forming YSO.ELETTRONICOenConference paper2004evn..conf..191GFIS/05 - ASTRONOMIA E ASTROFISICA