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| Paper: |
Kinematics of RR Lyrae Stars in the Inner and High Halos |
| Volume: |
92, Formation of the Galactic Halo. . . . Inside and Out |
| Page: |
141 |
| Authors: |
Layden, Andrew C. |
| Abstract: |
The kinematics of old stellar populations in different regions of the Galaxy place strong constraints on pictures of galaxy formation. Three new surveys which use RR Lyrae variables to trace the old stellar populations are discussed. The first is a local sample, containing stars within ~ 2.5 kpc of the Sun. The slow prograde rotation and moderate velocity dispersion of this sample are in good agreement with other tracers of the local halo. The second sample was chosen to lie at Galactocentric distances of 3--6 kpc, and to lie more than 2 kpc from the plane. The slow prograde rotation and very high velocity dispersion of this sample contrast strongly with the rotationally supported kinematics of the globular clusters in this region of the Galaxy. The third sample was chosen to lie more than 5 kpc from the plane, at roughly the solar circle. A slight retrograde rotation and a moderate velocity dispersion are observed. These kinematic results are compared with those of other halo tracers, and are interpreted in the context of the current scenarios of halo formation. |
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