, S.Guilloteau , R.Bachiller 
Institut de Radio Astronomie Millimétrique,
300 Rue de la Piscine, F-38406 Saint Martin d'Hères Centro Astronómico de Yebes (OAN, IGN). Apartado 148.
E-19080 Guadalajara, Spain 
synthesis image of the
red-shifted outflow lobe from the Class 0 protostar L 1448-mm. The
image is a 5-field mosaic obtained with the IRAM interferometer at
angular resolution. The SiO emission arises in a
highly-collimated jet extending over 0.2 pc. The jet consists of four
main blobs, probably corresponding to successive episodes of mass-loss
from the central object.
The kinematical structure of the jet is studied by the means of
velocity channel maps and position-velocity diagrams, and is
compared to current models of jet-driven bipolar outflows. We have
constructed a kinematical model of bow-shock to make such comparison
as detailed as possible. We find that most of the SiO
clumps delineate partial bow-shock structures, but important SiO emission is
also seen along the jet axis itself. Shock-processing
of the dust grains, and perhaps chemical gas-phase reactions in the
protostellar wind and in the mixing layer, could explain the
enhancement of SiO in the different jet blobs. The CO outflow in
L 1448, and perhaps in all bipolar outflows, is thought to be driven by
a primary jet ejected from the central star/disk system. We conclude
that, if not the primary wind itself, the material traced by the SiO
emission reported here is very closely linked to this primary jet.
Figure 3: SiO contour maps overlaid on the H 
emission (left),
and CO J=1-0 integrated intensity (right). The
arrow shows the global shift (6'') of the H emission from the
nominal position given by Bally et al. (1993, ApJ 418, 332),
who mentioned positional errors of 5''. The area covered by the
CO image (Bachiller et al., 1995, A&A 299, 857) is indicated by
the purple colour.
