Hs. Zhao, THE SURVIVAL OF THE SAGITTARIUS DWARF GALAXY AND THE FLATNESS OF THE ROTATION CURVE OF THE GALAXY, The Astrophysical journal, 500(2), 1998, pp. 149-152
How has the ''fluffy'' Sgr dwarf galaxy survived its 10-20 pericentric
passages in the halo of the Milky Way for a Hubble time? The scenario
that Sgr was deflected to its current orbit by the Magellanic Clouds
after a rendezvous on the north Galactic pole 2-3 Gyr ago is examined.
It is shown that the conditions of the collision fix both the sense o
f circulation of Sgr and the Large Magellanic Cloud around the Galaxy
and the slope of the Galactic rotation curve. The model argues that th
e two orthogonal polar circles traced by a dozen or so Galactic halo d
warf galaxies and globular clusters (Lh?C-SMC-Magellanic Stream-Draco-
Ursa Minor along l approximate to 270 degrees and M54-Ter 7-Ter 8-Arp
2-NGC 2419-Pal 15 along l approximate to 0 degrees) are streams of tid
al relies from two ancient galaxies that were captured on two intersec
ting polar rosette orbits by the Galaxy. Our results favor the interpr
etation of microlensing toward the LMC being due to source or lens sta
rs in tidal features of the Magellanic Clouds. We discuss direct and i
ndirect observations to test the collision scenario.