CO AND SHOCKED H-2 IN THE HIGHLY COLLIMATED OUTFLOW FROM VLA-1623

We show large-scale (CO)-C-12 and H-2 images of the outflow from the p roposed 'class 0' young star VLA1623. Shocked H-2 emission is clearly associated for the first time with this flow. Most of the H-2 lies in compact knots, each of which is downstream from a peak in the high-vel ocity CO. The total outflow mass derived from the CO data is 0.10 M(.) , most of which lies in the extended blueshifted south-east flow. The outflow in this direction is greater than or equal to 15 arcmin (0.7 p c) in length with an opening angle of less than or equal to 1.degrees 6. It can be divided into two regions: the first, within 0.07 pc of th e star, has a conical shape. Beyond this radius, the low-velocity CO h as a limb-brightened morphology, with a narrower, centrally peaked lan e at high velocities; this is indicative of flow along the walls of a cylindrical cavity. We suggest that most expansion of the outflow cavi ty occurs within the initial 0.07 pc of the source; beyond this, the m olecular flow is confined to a cylinder of constant width similar to 0 .03 pc. Comparison of the CO and H-2 results tends to suggest that the north-west side of VLA 1623 may contain two separate flows. The near- infrared continuum image shows the dense cloud around the VLA 1623 sou rce in silhouette against a background nebula. There is no evidence of elongation perpendicular to the outflow direction, and the core has a sharp outer radius of similar to 0.02 pc, with no evidence of a surro unding lower density accreting envelope. Fits to the radial distributi on of extinction indicate a Gaussian rather than shallow power-law den sity gradient.