ESCAPE OF T-TAURI STARS FROM YOUNG STELLAR-SYSTEMS

The decay of nonhierarchical few-body systems (N < 10) is examined by direct numerical integration to determine statistically how size, shap e, N, and rotation state influence the distribution of escape speeds f or ejected stars. The initial conditions are chosen to represent reali stic configurations for young stellar objects at the end of the accret ion phase in fragmented protostellar clouds. If we adopt typical prope rties for molecular cloud cores and assume system sizes deduced from i sothermal collapse calculations, we find that more than 60% of the esc apers have speeds > 3 km/s. We propose that high-velocity stars produc ed during the decay of young multiple star systems contribute signific antly to the halo of weak-line T Tauri stars recently discovered aroun d star forming regions by the ROSAT all-sky X-ray survey.