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| Paper: |
The Relationship of the Galactic Bulge to the Stellar Halo |
| Volume: |
92, Formation of the Galactic Halo. . . . Inside and Out |
| Page: |
24 |
| Authors: |
Rich, R. Michael |
| Abstract: |
Although an old, metal poor population is present in the inner bulge (R<1 kpc), we argue that this region is a stellar population separate from the classical stellar halo. The high stellar density and bar structure (affirmed by the success of Zhao's dynamical model) as well as the metal rich abundance distribution are best understood if the bulge is a separate stellar population. Even the metal poor populations of the bulge may not simply continue halo trends of metallicity. A population of centrally concentrated ``Disk'' globular clusters is present, but with a much larger scale height and less rotation than the bulge spheroidal population. While it has been proposed that these clusters are associated with the bulge and not the thick disk, we strongly caution that their spatial distribution bears little resemblance to the that of the dense inner bulge. The bulge also appears to have correlations between abundances and kinematics in its stars, a property that is not found in the halo population. However, recent turnoff photometry suggests that the bulge is approximately the same age as the old halo. Ortolani et al. (these proceedings) show that the age-sensitive parameter Delta V(HB}_{TO) =3.6 for the metal rich Galactic Center globular clusters, identical to within errors of the old halo clusters. We conclude that the bulge is a separate stellar population formed early in the history of the Galaxy, but that it is also distinct from the stellar halo. |
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