SYNCHROTRON EMISSION FROM THE H2O MASER SOURCE IN W3(OH)

We present a study of the radio continuum source found near the position of the H2O masers and the Turner-Welch source in the W3(OH) region. The source spectrum from 1.6 to 15 GHz exhibits a power law with spectral index -0.6. The continuum source is elongated in the east-west direction and its size decreases linearly with increasing frequency. These observations provide strong evidence for synchrotron emission from an inhomogeneous source. The elongated continuum source is coincident within 0.''1 of the center of expansion of the H2O masers and is aligned with the dominant H2O outflow pattern. A possible model for the system includes an early-type star with a fast collimated wind that drives a jetlike outflow. Fast shocks in the wind or jet accelerate electrons, via a first-order Fermi process, to relativistic speeds necessary for synchrotron emission. The jet impinges on the surrounding molecular material and shocks and accelerates this material, leading to the motions observed in the H2O masers.