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Impacts of Radial Mixing on the Galactic Thick and Thin Disks

Published online by Cambridge University Press:  02 August 2018

Daisuke Kawata*
Affiliation:
Mullard Space Science Laboratory, University College London, Holmbury St. Mary, Dorking, Surrey, RH5 6NT, UK email: [email protected]
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Abstract

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Using N-body simulations of the Galactic disks, we qualitatively study how the metallicity distributions of the thick and thin disk stars are modified by radial mixing induced by the bar and spiral arms. We show that radial mixing drives a positive vertical metallicity gradient in the mono-age disk population whose initial scale-height is constant and initial radial metallicity gradient is tight and negative. On the other hand, if the initial disk is flaring, with scale-height increasing with galactocentric radius, radial mixing leads to a negative vertical metallicity gradient, which is consistent with the current observed trend. We also discuss impacts of radial mixing on the metallicity distribution of the thick disk stars. By matching the metallicity distribution of N-body models to the SDSS/APOGEE data, we argue that the progenitor of the Milky Way’s thick disk should not have a steep negative metallicity gradient.

Type
Contributed Papers
Copyright
Copyright © International Astronomical Union 2018 

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