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 ce ntral exciting source. A highly collimated bipolar jet emanates from t his central source along a line between the source and HH 80-81. The j et consists of a multitude of knots, with a spacing of about 1400 AU a nd widths of less than 500 AU. This is strikingly similar to the struc ture 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. Th ese objects are detected and resolved at 6 cm and 3.6 cm with a spectr al index of alpha = -0.3. We find another resolved object 3.0 pc to th e north of the source along the well-defined flow axis and with the sa me negative spectral index, but without any known optical counterpart. We here call this object HH 80 North. The total projected dimension o f 5.3 pc for this highly collimated outflow complex far exceeds all ot her known HH complexes and is more than an order of magnitude larger t han 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 H H 80-81 jet and HH jets from low luminosity stars suggests that massiv e newborn stars pass through very similar evolutionary phases.