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2.5 Satellites of the Milky Way

These galaxies are excellent tools for studying the dark matter problem. Not only do their movement around the Galaxy lead to estimates of the total mass of the Galaxy or the Local Group, their internal dynamics show that they themselves are probably dominated by the dark matter.

Lin & Lynden-Bell (1982) studied the dynamics of the Magellanic Stream, and find that an extended dark halo is needed to model this complicated system. Lynden-Bell (1994) emphasizes the coincidence between the location of the Draco and Ursa Minor dwarf spheroidals and the Magellanic Stream along a great circle, as well as the possible existence of an older Fornax-Leo-Sculptor stream which could betray the orbital path of larger satellites. The recent HI map of Putnam et al. (1998) of the Magellanic system, with the detection of a possible leading stream, calls for a new study of the interaction between the Magellanic Clouds and our Galaxy, in order to get more insight in the extended dark halo around our Galaxy.