Discovery of a molecular hydrogen jet near IC 348

Abstract

We present near-infrared images of a newly discovered molecular hydrogen jet (HH 211) near the young stellar cluster IC 348 in the Perseus dark cloud complex. A wide-field true-color JHK' image locates HH 211 relative to the embedded source IC 348 IR, and a high-resolution image taken in the H2 upsilon = 1 - 0 S(1) line at 2.122 micrometers delineates the shock-excited gas. The jet is very young, with a dynamical age of less than 1000 yr. We suggest that the H2 emission arises in a turbulent sheath around the true jet, leading to an unusual symmetric limb-brightened appearance. This boundary layer is probably where ambient molecular material is being entrained to form a coincident bipolar CO outflow. We discuss possible models for the knots in HH 211, including internal working surfaces in an episodic outflow and crossing shocks in a recollimating jet. The exciting source of the jet and outflow was detected at lambda greater than or = 350 micrometers, and our observations imply that the exciting source is a young star deeply embedded in a dense NH3 core, perhaps an edge-on circumstellar disk. The HH 211 system of jet, molecular outflow, and embedded exciting source is the first discovered through near-infrared imaging.