HIGH-VELOCITY SULFUR MONOXIDE EMISSION FROM PROTOSTELLAR OUTFLOWS

We have mapped the J(N) = 2(3)-1(2), 3(2)-2(1) and 6(5)-5(4) transitio ns of SO and the J = 5-4 transition of SiO in nine regions containing protostellar molecular outflows. We find that, in general, the spatial pattern of the SO emission and shape of the line profiles is differen t for each transition. In the quiescent gas, the SO emission is widesp read in the ambient clouds, but J(N) = 2(3)-1(2) and J(N) = 3(2)-2(1) emission is relatively weak in the warm, dense cores around the young stars, while the J(N) = 6(5)-5(5) emission is found to be strongest in the cores. In the outflowing gas, the SO 6(5)-5(4) line is detected t oward the outer parts of the CO Iobes and shows high-velocity (HV: 5-3 2 km s(-1)) wings, while the SO J(N) = 3(2)-2(1) and J(N) = 2(3)-1(2) emission is not detected. SiO J = 5-4 shows similar HV emission to SO J(N) = 6(5)-5(4), but little emission from the quiescent gas. In gener al, SO and SiO emission from the outflow does not resemble maps or lin e profiles of CO, CS, NH3, or HCO+. These results give further support that lines of SO and SiO can be very useful as specific tracers of sh ocked gas in outflows. The observations presented here are not easily explained with the current shock models.