IAU Symposium Abstract S186-014P

The Magellanic Stream Revisited - The Halo Mass of the Galaxy in the Range of 100 kpc -

T. Murai
Department of Physics, Nagoya University < murai@ibm.net >

There is still a controversy on the mass of the Galaxy in the deep ha lo, some still advocates a conservative view where the rotation velocity ultim ately decays as in accord with the Keplerian law at the distance of 50 kpc, while others become to consider that the rotation curve of the Milky Way, e ssentially, stays flat or is still increasing at the distance of the Magellanic C louds and the Magellanic Stream. On the Basis of the accurate observed data of the spacial location of the LMC, SMC and the Magellanic Stream and their radial velocity distribution, it is clarified that the halo of the Galaxy ha s a huge dark matter, resulting in a flat rotation curve with the terminal velocity of the order of 250 km/s. It is shown that the tidal interaction of the LMC and t he SMC has produced a number of charcteristics, a series of burst of star fo rmation, kinematic peculiarities within the both Clouds, collision-induced imp rints, etc. All have, observationally, been revealed and interpreted as a result of at leased two colse encounters of the LMC and the SMC, which can occur o nly in the deep gravitational potential of dark matter as shown by a tida l simulation of Murai and Fujimoto(1980).