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Thin and Thick Galactic Disks

Poul E. Nissen
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Abstract

Studies of elemental abundances in stars belonging to the thin and the thick disk of our Galaxy are reviewed. Edvardsson et al. (1993) found strong evidence of [alpha/Fe] variations among F and G main sequence stars with the same [Fe/H] and interpreted these differences as due to radial gradients in the star formation rate in the Galactic disk. Several recent studies suggest, however, that the differences are mainly due to a separation in [alpha/Fe] between thin and thick disk stars, indicating that these populations are discrete Galactic components, as also found from several kinematical studies. Further evidence of a chemical separation between the thick and the thin disk is obtained from studies of [Mn/Fe] and the ratio between r- and s-process elements. The interpretation of these new data in terms of formation scenarios and time scales for the disk and halo components of our Galaxy is discussed.

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Poul E. Nissen. 2003-10-13. Thin and Thick Galactic Disks. https://arxiv.org/abs/astro-ph/0310326

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