Resumen
High-Resolution simulations of cosmological structure formation suggest the formation of dark matter halos with strong substructure. These small clumps can spiral into the center of the massive halo on a short timescale and be accreted in a minor merger. If a stellar disk is already present this disk will be heated and puffed up. We compared N-body simulations of these minor mergers with observations of the velocity distribution of a sample of Milky Way stars.