N-BODY SIMULATIONS OF THE SMALL MAGELLANIC CLOUD AND THE MAGELLANIC STREAM

An extensive set of N-body simulations has been carried out on the gra vitational interaction of the Small Magellanic Cloud (SMC) with the Ga laxy and the Large Magellanic Cloud (LMC). The SMC is assumed to have been a barred galaxy with a disc-to-halo mass ratio of unity before in teraction and was modelled by a large number of self-gravitating parti cles, whereas the Galaxy and LMC have been represented by rigid spheri cal potentials. Our more advanced numerical treatment has enabled us t o obtain the most integrated and systematic understanding to date of n umerous morphological and kinematical features observed in the Magella nic system (excluding the LMC), which have been dealt with more or les s separately in previous studies. The best model we have found succeed ed in reproducing the Magellanic Stream (MS) as a tidal plume created by the SMC-LMC-Galaxy close encounter 1.5 Gyr ago. At the same time, w e see the formation of a leading counterpart to the Magellanic Stream (the leading arm), on the opposite side of the Magellanic Clouds to th e Stream, which mimics the overall distribution of several neutral hyd rogen clumps observed in the corresponding region of the sky. A close encounter with the LMC 0.2 Gyr ago created another tidal tail and brid ge system, which constitutes the interCloud region in our model. The e longation of the SMC bar along the line-of-sight direction suggested b y Cepheid observations has been partially reproduced, alongside its pr ojected appearance on the sky. The model successfully explains some ma jor trends in the kinematics of young populations in the SMC bar and o lder populations in the 'halo' of the SMC, as well as the overall velo city pattern for the gas, young stars, and carbon stars in the interCl oud region.