NEAR-INFRARED OBSERVATIONS OF THE HH-111 REGION

We have obtained near-infrared K-band images of the HH 111 region, and detected, besides the HH 111 jet itself, a new optically invisible bipolar jet here called HH 121, from the source region of HH 111, but at large angles to the HH 111 flow axis. Near-infrared long-slit spectra of both jets confirm their emission-line nature. Radial velocities derived from H-2 lines show that the northern lobe of HH 121 is approaching and the southern is receding, but the velocities are so low that the system is likely to lie almost in the plane of the sky. There is a considerable angle between the two lobes of HH 121. The HH 111 and HH 121 jets intersect within an arcsecond of a VLA source, and we interpret the observations as two bipolar jets emanating from a putative pre-main-sequence binary, a situation very similar to the HH 1/2 region. Tidal forces could effect significant precession and disturbance of the disk around the lower mass stellar component, possibly causing the large discrepancy between the flow axes of HH 111 and HH 121 and between the lobes of HH 121 itself. Near-infrared [Fe II] lines have been used to derive electron densities (n(e) almost-equal-to 2000 cm-3) and extinction (A(V) almost-equal-to 5-6 mag) in parts of the HH 111 jet, and H-2 lines were employed to derive an excitation temperature of about 2150 K.