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Paper: Abundance Gradients in the Galactic Bulge and Halo
Volume: 147, Abundance Profiles: Diagnostic Tools for Galaxy History
Page: 36
Authors: Rich, R. Michael
Abstract: I discuss abundance gradients in the Galactic bulge and halo. In the bulge, there is evidence for an abundance gradient in [M/H] of 0.4 dex/kpc. However, photometric and spectroscopic measures of metal abundance disagree, and the apparent gradient may actually represent a population transition between the bulge and the inner halo. There is no convincing evidence for an abundance gradient in the Galactic halo, but there is almost certainly an age gradient, in the sense that the outer halo is slightly younger than the inner halo. The galactic globular cluster system is divided between bulge and halo globular clusters; when the separation is made, there is also little evidence for an abundance gradient within either system. The abundance gradient in the bulge is consistent with a wind-driven chemical evolution scenario, which may be related to the wide dispersal of metals in the early Universe.
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