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Paper: Exploring the Milky Way Disk Abundance Transition Zone RGC ∼ 10 kpc with Open Clusters
Volume: 396, Formation and Evolution of Galaxy Disks
Page: 73
Authors: Jacobson, H.R.; Pilachowski, C.A.; Friel, E.D.
Abstract: Recent studies of the radial abundance distribution among stellar populations in the Galactic disk have shown a change in the abundance trend at galactocentric distance RGC ∼ 10 kpc, as first noted by Twarog et al. (1997). Here the gradient in [Fe/H] with distance appears to vanish, with abundances of stars at greater distances dropping to [Fe/H] ∼ −0.5, independent of galactocentric distance. Also, [α/Fe] > 0 for Rgc > 10 kpc, contrasted to the solar ratios exhibited by clusters interior to 10 kpc (Yong et al. 2005). This implies that the outer disk has undergone a different star formation history than the inner disk. However, abundances of many more stars at RGC ∼ 9−12 kpc must be determined to characterize the nature of the transition from inner to outer disk. To that end, we have initiated a spectroscopic survey of a large sample of open clusters in this region, which we describe here.
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