OBSERVATIONS AND SHOCK-MODELS OF THE JET AND HERBIG-HARO OBJECTS HH-46/47

We present new monochromatic images, long-slit echelle spectra, and theoretical position-velocity diagrams of the Herbig-Haro objects HH 46 and HH 47. The outer bow shock HH 47D extends almost all the way back to the infrared source driving the outflow in a narrow-band [O II] image of the region, but is not easily visible in Hα and [S II]. We confirm the discovery of a counterjet in [S II] reported by Reipurth. Long-slit spectra of HH 47D show a "hook" shape in position-velocity space which can be understood in terms of a spatially resolved bow shock moving at an angle roughly 45° to the line of sight. The object HH 47A at the end of the jet also appears to be a bow shock rather than a Mach disk as has been suggested previously. The presence of two bow shocks within a single outflow is not predicted from a simple continuous jet model, but can be understood if the outflow is episodic or if both a disk wind and a stellar wind are present in the system.