Echelle spectroscopy of H-2 in the HH111 jet

Near-Infrared echelle spectra of the Herbig-Haro knots F-P in the western l obe of the HH 111 out ow are presented. 10 adjacent, parallel slit position s were observed so that the kinematics could be mapped across the width of the ow. We find broad (FWZI similar to 100 km s(-1)), two-component H-2 pro files in the knots nearest the source; the profiles converge to a single, i ntermediate-velocity peak (V-LSR similar to 50 km s(-1)) at knot P.The kine matic signature of the HH 111 jet in H-2 is very similar to that seen at op tical wavelengths (from both radial and tangential velocity measurements). In conjunction with published proper-motion (knot/shock pattern speed) meas urements, we interpret the data in terms of a simple geometrical bow shock model. The model infers a high pre-shock velocity, of the order of 200-250 km s(-1), with H-2 excitation in the extended bow wings in knots L, H and F , though exclusively near the bow head in knot P, with probably C-type shoc k excitation throughout.