Velocity structure in the Canis Major R1 molecular clouds

Abstract

We have mapped CO emission over a 5/sup 0/ x 5/sup 0/ area in the Cains Major OB1/R1 region. Most of the emission is confied to an elliptical region of approximately 90 x 60 pc. Several CO emission peaks appear, many associated with reflection nebulae. While most of the emission falls in the LSR velocity range 10--20 km s/sup -1/, we find some material over the full velocity covered (-30 to +45 km s/sup -1/). There is no simple pattern that would indicate a single expanding shell, but the observations are consistent with the idea that some energetic process, which took place in an initially inhomogeneous cloudy medium, was responsible for the observed morphology of the region. Simple arguments suggest that a supernova explosion is the most likely candidate for this energetic process. The relationship between the process that shaped the clouds and star formation in the region is discussed.