We present observational studies of the molecular outflow associated with the Class 0 young stellar object toward L1157. The CO emission shows a well-collimated bipolar morphology with rich structure. In addition to the extended emission, the CO gas is found in clumps in the vicinity of the near-infrared H2 emission. The SiO emission is seen in six prominent condensations, three on each side of the protostar. They appear to be in three pairs; each pair aligns well with the exciting star. The CS emission imaged toward the blueshifted outflow is well collimated and presents a bow-shaped structure coincident with the SiO and H2. A comparison of the outflow in different tracers suggests that the molecular gas is entrained at the head of an underlying jet. The jet seems to be episodic and shows signs of deceleration as it ploughs through the dense core.
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