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The Metallicity Distribution Functions of SEGUE G and K dwarfs: Constraints for Disk Chemical Evolution and Formation | | Katharine J. Schlesinger
; Jennifer A. Johnson
; Constance M. Rockosi
; Young Sun Lee
; Heather L. Morrison
; Ralph Schoenrich
; Carlos Allende Prieto
; Timothy C. Beers
; Brian Yanny
; Paul Harding
; Donald P. Schneider
; Cristina Chiappini
; Luiz N. da Costa
; Marcio A.G. Maia
; Ivan Minchev
; Helio Rocha-Pinto
; Basilio X. Santiago
; | | Date: |
9 Dec 2011 | | Abstract: | Using the G and K dwarfs from the Sloan Extension for Galactic Understanding
and Exploration (SEGUE) survey, we determine the metallicity distributions of
cool stars in the Milky Way disk system. This portion of the Sloan Digital Sky
Survey (SDSS) contains spectra for approximately 41,500 G and 23,800 K dwarfs,
a larger sample, numerically and spatially, than previous spectroscopic
analyses. SEGUE has a quantitative target-selection algorithm which we use to
ensure that our sample accurately represents the underlying Milky Way
populations. Using estimated distances, with uncertainties of 12%, we quantify
the variation in metallicity with respect to spatial position from the Galactic
center (R) and the plane of the Galaxy (|Z|). We are consistent with the
results from Cheng et al., estimating a negative gradient below |Z| of 1 kpc
that flattens above this height. Both spectral types also exhibit a consistent
decrease in [Fe/H] with increasing |Z|, approximately -0.3 dex/kpc, which
reflects the transition from a thin-disk-dominated sample at small |Z| to a
sample consisting primarily of thick-disk stars at heights above |Z| of 1 kpc.
We compare our distributions to those of two different models of the Galaxy,
neither of which is able to replicate the metallicity distributions we observe
above |Z| of 0.5 kpc, likely because they are calibrated on
thin-disk-dominated, local samples. Our unbiased observations of G and K dwarfs
provide valuable constraints for chemical and dynamical Galaxy evolution
models, with particular utility for thin- and thick-disk formation theory.
(edited) | | Source: | arXiv, 1112.2214 | | Services: | Forum | Review | PDF | Favorites | |
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