High-resolution images of the L1551 molecular outflow. II - Structure and kinematics

The authors present complete maps of the high-velocity 12CO emission in the L1551 bipolar molecular outflow, for which the angular resolution has been enhanced by maximum entropy, and a 13CO map of the entire L1551 molecular cloud. The molecular wind has been swept into a thin shell which completely surrounds a cavity now mostly devoid of molecular gas. The shell at the ends of the outflow is progressing through the cloud, and has broken out of the cloud at one position, where, unimpeded by the ambient gas, the molecular wind is being reaccelerated. Optical depth measurements show that the mass of outflowing molecular gas may be more than 3.5 M_sun;, which is nearly one-tenth of the mass of the entire cloud. A model is proposed, in which the molecular material has been swept up by an ultra-high velocity, perhaps latitude-dependent, wind originating at or near IRS 5.