On the origin of high-eccentricity halo stars

The present-day chemical and dynamical properties of the Milky Way aresignatures of the Galaxy's formation and evolution. Using a selfconsistent chemodynamical evolution code we examine these properties within the currently favoured paradigm for galaxy formation –hierarchical clustering within a CDM cosmology.Our Tree N-body/SmoothedParticle Hydrodynamics code includes a self-consistent treatment ofgravity, hydrodynamics, radiative cooling,star formation, supernova feedback and chemical enrichment. Two models are described whichexplore the role of small-scale density perturbations in drivingthe evolution of structure within the Milky Way. The relationship betweenmetallicity and kinematics of halo stars are quantified and the implicationsfor galaxy formation discussed. While high-eccentricityhalo stars have previously been considered a signature of 'rapid collapse', we suggestthat many such stars may have come from recently accreted satellites