The Dynamics of the Large Magellanic Cloud Periphery: Mass Limit and Polar Ring

Radial velocities of 759 carbon stars on the periphery of the LMC are used to determine the rotation curve from 3 to 12 kpc. After a peak of 42 km s -1 at 4 kpc, the velocities decline to 35 km s -1 at 6.5 kpc, suggesting that 90% of the LMC's matter lies inside this radius. The rising velocities seen at larger radii are explained by particle-particle N -body simulations as arising from tidal interactions between LMC and both the SMC and the Galaxy. For an inclination of 33° the mass contained within a 5 kpc radius is 6.2 ± 0.9 × 10 9 M ☉ . An upper limit on the LMC halo mass is determined.