HIGHLY COLLIMATED MOLECULAR-HYDROGEN JETS NEAR IRAS 05487- NEAR-INFRARED IMAGING AND SPECTROSCOPY(0255 )

We present new narrowband near-infrared images together with K-band sp ectra of highly collimated bipolar jets close to the IRAS 05487+0255 s ource. The jets are located similar to 50 '' west of the Herbig-Haro 1 10 outflow. The jets are not visible at optical wavelengths and theref ore do not fall into the ''standard'' Herbig-Haro object classificatio n scheme. Nevertheless, they belong to an ever growing group of molecu lar hydrogen jets associated with young stellar objects that are optic ally undetected. The jets are very well collimated, with length-to-wid th ratios of similar to 10-20. The spectra of the jet and its counterj et in the K band show a limited number of H-2 emission lines that make it difficult to obtain an accurate excitation temperature. We estimat e T-ex = 1104+/-67 K and T-ex = 920+/-156 K for the red and blue jet c omponents, respectively. The radial velocities of the jet and counterj et, based on the shift of the (1,0) S(1) 2.121 mu m line, are similar to-275+/-50 km s(-1) and similar to 180+/-50 km s(-1), respectively, s uggesting an angle of similar to 30 degrees-45 degrees between the jet and the line of sight. The H-2 emission di the entire jet extends for ar least 40 '', similar to 0.1 pc at the distance of Orion. If the fl ow velocity is comparable to that of the radial velocities, then the d ynamical age of the system is quite short (similar to 500 yr), consist ent with a young jet arising from an embedded source. Entrainment in a turbulent mixing layer may explain this morphology and spectral chara cter.