Abstract
ABSTRACT. A model for the origin of the Orion and Monoceros molecular complexes, located b 150 pc away from the galactic plane, is presented. The model is based on two-dimensional hydrodynamic simulations for the interaction of high-velocity clouds and the disk of the Galaxy. Cloud- galaxy collisions generate massive shocked layers and the self-gravity of these shocked layers can then trigger the formation of molecular clouds. The motion of molecular clouds formed by this process reflect the original motion of the shocked layers and the clouds reach positions located for away from the plane. The mass, location, and rotation observed in Orion and Monoceros can be explained by a collision of a cylindrical cloud near the solar neighborhood. Both molecular complexes were formed, some 6 X lO yr ago, when the original shocked layer was fragmented by galactic tidal forces, and their angular momentum simply comes from galactic differential rotation. Kaq WOJt : INTERSTELLAR-CLOUD
