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Evolution of the Galactic Halo and Disk

Published online by Cambridge University Press:  07 August 2017

Gerard Gilmore
Gerard Gilmore*
Affiliation:
Institute of Astronomy, Madingley Road, Cambridge CB3 0HA, UK ([email protected])

Abstract

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Correlations between stellar kinematics and chemical abundances are fossil evidence for evolutionary connections between Galactic structural components. Extensive stellar surveys show that the only tolerably clear distinction between galactic components appears in the distributions of specific angular momentum. Here the stellar metal-poor halo and the metal-rich bulge are indistinguishable from each other, as are the thick disk and the old disk. Each pair is very distinct from the other. This leads to an evolutionary model in which the metal-poor stellar halo evolves into the inner bulge, while the thick disk is a precursor to the thin disk. These evolutionary sequences are distinct. The galaxy is made of two discrete “populations”, one of low and one of high angular momentum. Some (minor?) complexity is added to this picture by the debris of late and continuing mergers, which will be especially important in the outer stellar halo.

Type
Session 3: Open Clusters and the Galactic Disk
Information
Symposium - International Astronomical Union , Volume 164: Stellar Populations , 1995 , pp. 99 - 107
Copyright
Copyright © Kluwer 1995 

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