2006PASJ...58..883I

We report on H₂O masers associated with the massive-star forming region G192.16-3.84 observed with the new Japanese VLBI network at three epochs spanned for two months, which have revealed the three-dimensional kinematical structure of the whole H₂O maser region in G192.16-3.84, containing two young stellar objects separated by ∼ 1200AU. The maser spatio-kinematical structure has well persisted since previous observations, in which the masers are expected to be associated with a highly collimated bipolar jet and an infalling-rotating disk in the northern and southern clusters of H₂O maser features, respectively. We estimated a jet expansion speed of ∼ 100km/s and re-estimated the dynamical age of the whole jet to be 5.6 x 10⁴yr. We investigated the spatial distribution of the Doppler velocities during the previous and present observations and the relative proper motions of H₂O maser features in the southern cluster, as well as the relative bulk motion between the two maser clusters. They are well explained by a model of an infalling-rotating disk with a radius of ∼ 1000AU and a central stellar mass of 5-10M_☉, rather than by a model of a bipolar jet perpendicular to the observed CO outflow. Based on the derived H₂O maser spatio-kinematical parameters, we discuss the formation mechanism of the massive young stellar objects and the outflow development in G192.16-3.84.