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The jet-driven molecular outflow in L 1448: CO and continuum synthesis images

R. Bachiller , S. Guilloteau , A. Dutrey , P. Planesas , J. Martin-Pintado
Centro Astronómico de Yebes, Apartado 148, E-19080 Guadalajara, Spain
Institut de Radio Astronomie Millimétrique, 300 rue de la Piscine, F-38406 Saint Martin d'Hères, France
Abstract: The central region of the L1448 molecular outflow has been mapped in the CO J=1-0 line, and in the 2.6 mm continuum, with angular resolution of ( 4 10 pc at the distance of L 1448, 300 pc). In the mapped area, there are two partially overlapping outflows emerging from two different continuum sources (L 1448/IRS3 and L 1448-mm).

The continuum maps are used to study the nature of the two exciting sources. The strong mm peak around L 1448/IRS3 is coincident in position with the VLA cm source L 1448N(B), and it likely is the source driving the outflow in the northern region. L 1448-mm is at the origin of the main outflow. The spectral energy distributions confirm that both sources (L 1448-mm and IRS3) are among the youngest known protostellar candidates (``Class 0" sources)

New details on the structure of the L 1448-mm outflow are revealed by the CO observations. Weak line emission at extremely-high velocities is detected along the jet which is at the axis of the outflow. Such emission is associated with the molecular bullets detected with single-dish telescopes. The jet is inclined at PA , and its actual jet speed is in excess of 200 km.s.

Limb-brightened cavities are detected at low CO velocities. The cavities have a biconical morphology, suggesting that a bipolar nebula is forming. The formation of the cavity is well explained in the frame of models for jet-driven bipolar outflows, where the jet entrains ambient molecular material through the propagation of large bow-shocks which are able to disturb the ambient gas at long transverse distances from the jet axis. A comparison of the CO data with H images at 2.12 m provides further support to this scenario.

The blue shifted lobe of the L 1448-mm outflow exhibits a continuous bending that can be explained as a result of direct collision of the two outflows in L 1448.

next up previous contents
Next: Detection of MgCN Up: Scientific Results Previous: Hydrogen Recombination --Lines

Robert Lucas
Fri Mar 17 14:32:02 MET 1995