High-velocity molecular outflows in the infrared near young stellar objects.

Several luminous embedded young stellar objects have been observed at high resolution (0.057 cm^-1) in the 4.7 μm region using the FTS on the CFH telescope. The authors present the results obtained on one of these sources, GL 2591. The spectrum shows the lines of the fundamental vibration-rotation band of CO with strong blueshifted components. The outflowing gas is warmer than the ambient cloud, with a temperature as high as 1012K in the hottest parts. It consists of discrete velocity components with an extreme velocity of more than 150 km s^-1 with respect to the ambient molecular cloud. The authors interpret the absorptions as being due to gas near the central object and flowing from it. These flows, unobservable in microwave, raise the question of the role they play in the formation of the large-scale bipolar outflows.