Velocity Distribution of Stars in the Pup-CMa Association

The distribution of proper motions of stars in the Pup-CMa association is presented. The stars' velocities are approximately parallel to each other, which indicates that the stars are close together in space. The mutual distribution of stars and molecular clouds in the association is interpreted as proof that the stars emerged from a single gigantic primordial molecular cloud (or several large clouds), destroyed by radiation and/or stellar wind coming from those stars. It is assumed that part of that cloud is being dissipated, while part is being broken into several small clouds, which we are observing at present.