Stellar streams: origin and evolution
We have made a statistical analysis of the space velocity distribution for stars in the solar neighbour-hood. Three large, probably non-random stellar streams were revealed. Those correspond to well-known moving clusters: Hyades, Pleiades and UMa. Small clumps of stars were found within the streams. We have estimated the statistical significance of these groups. We found that massive high-precision data (proper motions, parallaxes and radial velocities) are necessary for studying the fine structure of the streams. Various scenarios for streams formation are discussed: the decay of open clusters, the presence of superclusters, and the perturbations from spiral arms. The evolution of streams in a smoothed Galactic gravitational field is studied. We take into account the interactions between stream stars and giant molecular clouds (GMC). The dependence of the lifetimes of four streams on the adopted stream size rc in coordinate space were estimated. When rc=200Âpc, the mean lifetime is about 1 Gyear. Interactions with GMCs can shorten the mean lifetimes by as much as a fifth.
Document Type: Research Article
Publication date: April 1, 2006