Discovery of a Near-Infrared Jet-Like Feature in the Z Canis Majoris System

Abstract

We present near-infrared high resolution observations of the young binary system Z Canis Majoris using the adaptive optics system at the Keck-II telescope. Both components are unresolved at 1.25 and 1.65 microns, although high dynamic range images reveal a previously unknown jet-like feature in the circumstellar environment. We argue that this feature probably arises from light scattered off the walls of a jet-blown cavity, and proper motion studies of this feature can probe the dynamics of the bipolar outflow. Potentially, the morphology of the dust-laden cavity walls offers a new probe of the momentum profile and collimation of bipolar winds from young stellar objects. We also derive high precision binary parameters, which when combined with historical data have allowed the first detection of orbital motion. Lastly, our observations confirm the high degree of flux variability in the system; the North-West binary component is dominant at H-band, in contrast to all previous observations.