DO DWARF SPHEROIDAL GALAXIES CONTAIN DARK-MATTER

The amount of dark matter in the four Galactic dwarf spheroidal galaxi es with large mass-to-light ratios is investigated. Sextans has a cuto ff radius that is equal to the expected tidal radius, assuming a high mass-to-light ratio. This satellite very likely is dark matter-dominat ed. Carina, Ursa Minor, and Draco, on the other hand, cannot contain a dominating dark matter component if the observed ''extratidal'' stars are located exterior to the tidal radii of these systems. The evidenc e for tidal stripping in the absence of dark matter is also supported by the fact that the observed cutoff radii of all three satellites are equal to their tidal radii, assuming a low, globular cluster-like mas s-to-light ratio. The large velocity dispersions of these galaxies, on the other hand, provide strong evidence for a massive dark matter com ponent. In this case, the ''extratidal'' stars lie deeply embedded in the dark matter potential wells of the satellites. These stars then wo uld represent a gravitationally bound, extended stellar component of u nknown origin.