SiO emission as a tracer of shocked gas in molecular outflows

Observations and limited mapping of the J=2−1, J=3−2 and J=5−4 lines of SiO toward the molecular outflows in L1448, B1, NGC 2071 and Cepheus A are presented. A single transition of SO, H 13 CO + , H 13 CN and HN 13 C was also measured toward these sources. The SiO profiles are very different from those of the other molecules. In contrast to the narrow lines (0.8−3 km/s) observed in H 13 CO + , H 13 CN and HN 13 C, typical of the ambient quiescent gas in these clouds, the SiO profiles exhibit remarkable broad linewidths (7 to 50 km/s)