Dwarf Galaxies and the Galactic Halo

Dwarf galaxies like the Magellanic Clouds play a major role in the formation and evolution of the Galactic halo. These systems, with respect to the Milky Way, illustrate typical examples of minor merging events, the collision of galaxies that differ in mass by at least a factor of ten. In a minor merger, tidal forces from the larger galaxy are capable of gradually stripping material (dark matter, stars and gas) from the satellite galaxy, that after several orbital periods gets fully disrupted. The best methodology to detect the tidal debris of disrupted satellites combines information on the position, motion, and chemical composition of individual tracers. Minor mergers occur frequently in the Universe and a more comprehensive knowledge of such mergers will allow us to better understand hierarchical structure formation in a cosmological context.