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| Paper: |
The Space Motion and Extent of the Sagittarius Dwarf Galaxy |
| Volume: |
92, Formation of the Galactic Halo. . . . Inside and Out |
| Page: |
84 |
| Authors: |
Irwin, Mike; Ibata, Rodrigo; Gilmore, Gerry; Wyse, Rosie; Suntzeff, Nick |
| Abstract: |
A new companion galaxy to the Milky Way was discovered recently in the constellation of Sagittarius (Ibata et al. 1994). Though it is not directly visible on photographic plates its member stars can be identified unambiguously by combining photometric and radial velocity measurements. To date over one thousand kinematically confirmed members and many tens of thousands of photometrically selected candidate stars have been found over a very large area of sky, ~ 22(deg) times 7(deg) , in the Southern Galactic Hemisphere. By direct comparison of Sgr colour-magnitude diagrams with equivalent diagrams for other Galactic satellites (Ibata et al. 1994; Ibata et al. 1995) and from the apparent magnitude of RR Lyrae member stars (Mateo et al. 1995) it was deduced that the current position of this galaxy is approximately 16 kpc from the Galactic centre, making Sgr the closest known satellite galaxy of the Milky Way. We present here an update on our current knowledge of this important system, with particular emphasis on its morphological appearance, spatial extent and likely mass, and a preliminary report on its kinematics and space motion. |
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