Observations by Gwinn, Moran, and Reid of the proper motions of water masers in W49N show that they have an elongated distribution expanding from a common center. Features with high space velocity only occur far from the center, while low-velocity features occur at all distances. It is proposed that water masers in star-forming regions occur in expanding shells swept up by high-velocity winds from young, massive stars during the early phases of the expansion. In W49N, confinement of the bubble by a density distribution with an axial cavity can explain both the velocity field and the shape of the maser distribution. A fully dynamical calculation of the expanding bubble is presented which provides a satisfactory fit for the observations and suggests that this system is only ~250 yr old. Thus these observations may show the very first stages of the formation of a jet from a young stellar object.
Digital Object Identifier (DOI)
Low, Mordecai-Mark Mac and Elitzur, Moshe, "Water Masers in W49N - The Youngest Stellar Jet?" (1992). Physics and Astronomy Faculty Publications. 230.