HH 80-81 - A HIGHLY COLLIMATED HERBIG-HARO COMPLEX POWERED BY A MASSIVE YOUNG STAR

We present multifrequency, matching-beam VLA continuum observations of the HH 80-81 system as well as high-resolution observations of its central exciting source. A highly collimated bipolar jet emanates from this central source along a line between the source and HH 80-81. The jet consists of a multitude of knots, with a spacing of about 1400 AU and widths of less than 500 AU. This is strikingly similar to the structure of HH jets emanating from young stars more than a thousand times less luminous. The southern lobe terminates in the visible HH objects HH 80 81 at a projected distance of 2.3 pc from the central source. These objects are detected and resolved at 6 cm and 3.6 cm with a spectral index of alpha = -0.3. We find another resolved object 3.0 pc to the north of the source along the well-defined flow axis and with the same negative spectral index, but without any known optical counterpart. We here call this object HH 80 North. The total projected dimension of 5.3 pc for this highly collimated outflow complex far exceeds all other known HH complexes and is more than an order of magnitude larger than the typical dimensions of such flows. There is clear evidence for a gentle wiggling of the flow axis, suggesting that the driving source may be precessing. The remarkable structural similarity between the HH 80-81 jet and HH jets from low luminosity stars suggests that massive newborn stars pass through very similar evolutionary phases.