Proper motions of young stars in Chamaeleon I. A Virtual Observatory study of spectroscopically confirmed members

Received; accepted Context. The study of the motion of the members of a given open cluster or stellar association provides key information about their formation and early evolution. The Chamaeleon cloud complex constitutes one of the closest and best studied low-mass star-forming regions in the Galaxy. Aims. We want to provide further evidence of the origin of the proposed stellar members of Chamaeleon and to identify interlopers from the foreground Cha and η Cha associations. Methods. We compile lists of spectroscopically confirmed members of Chamaeleon I and II, Cha and η Cha, and of background objects in the same line of sight. Using Virtual Observatory tools, we cross-match these lists with the UCAC3 catalogue to get the proper motions of the objects. In the vector point diagram, we identify the different moving groups, and use this information to study the membership of proposed candidate members of the associations from the literature. For those objects with available radial velocities, we compute their Galactic space velocities. We look for correlations between the known properties of the objects and their proper motions. Results. The members of the dark clouds exhibit clearly different proper motions from those of the foreground associations and of the background stars. The data suggest that Chamaeleon II could have different dynamical properties from Chamaeleon I. Althoug