Distinction of parallel outflows in L1448 through H2 excitation

High-resolution infrared maps of the emission from warm molecular gas in the L1448 outflow region are presented. Comparison of images from H2 lines produced from the first and second vibrational levels demonstrates the presence of two distinct parallel outflows. The main outflow (from the L1148-mm source) is of high excitation and shows remarkably little spatial variation in the 1-0 S(1)/2-1 S(1) intensity ratio, which remains near 10 across the whole ridge. Two explanations are offered: (a) the ridge consists of numerous fine-scale C-type bow shocks and/or (b) supersonic turbulence in a shear layer generates a C-type self-similar shock velocity distribution. The second outflow (from the IRS 3 source) is of low excitation, suggesting a combination of lower density and temperature.