3 - The Clouds as galaxies

Summary

It is essential for our understanding of the evolution of the Magellanic System, comprising the LMC and the SMC, the InterCloud (IC) or Bridge region and the Magellanic Stream, to know the motions of its members in the past. The Clouds have a common envelope of neutral hydrogen. This indicates that they have been bound to each other for a long time. It is generally assumed, but not definitely proven, that the Clouds have also been bound to our Galaxy for at least the last 7 Gyr. Most models assume that the Clouds lead the Magellanic Stream. The Magellanic System moves in the gravitational potential of our Galaxy and in the plane defined by the Local Group It is also exposed to ram pressure through its movement in the galactic halo. The influence of our Galaxy ought to be noticeable in the present structure and kinematics of the System.

The interaction between the Clouds has influenced their structure and kinematics severely. It should be possible to trace the effects as pronounced disturbances in the motions of their stellar and gaseous components. Recent astrometric contributions in this field show great promise for the future if still higher accuracy can be achieved. It should be kept in mind in all analyses that results of interactions may be expected everywhere.