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The SEGUE stellar parameter Pipeline. V. estimation of alpha-element abundance ratios from low-resolution SDSS/SEGUE stellar spectra

Title
The SEGUE stellar parameter Pipeline. V. estimation of alpha-element abundance ratios from low-resolution SDSS/SEGUE stellar spectra
Authors
Lee Y.S.Beers T.C.Prieto C.A.Lai D.K.Rockosi C.M.Morrison H.L.Johnson J.A.An D.Sivarani T.Yanny B.
Ewha Authors
안덕근
SCOPUS Author ID
안덕근scopus
Issue Date
2011
Journal Title
Astronomical Journal
ISSN
0004-6256JCR Link
Citation
vol. 141, no. 3
Indexed
SCI; SCIE; SCOPUS WOS scopus
Abstract
We present a method for the determination of [α/Fe] ratios from low-resolution (R = 2000) SDSS/SEGUE stellar spectra. By means of a star-by-star comparison with degraded spectra from the ELODIE spectral library and with a set of moderately high-resolution (R = 15, 000) and medium-resolution (R = 6000) spectra of SDSS/SEGUE stars, we demonstrate that we are able to measure [α/Fe] from SDSS/SEGUE spectra (with S/N>20/1) to a precision of better than 0.1 dex, for stars with atmospheric parameters in the range T eff = [4500, 7000] K, log g = [1.5, 5.0], and [Fe/H] = [-1.4, +0.3], over the range [α/Fe] = [-0.1, +0.6]. For stars with [Fe/H] <-1.4, our method requires spectra with slightly higher signal-to-noise to achieve this precision (S/N>25/1). Over the full temperature range considered, the lowest metallicity star for which a confident estimate of [α/Fe] can be obtained from our approach is [Fe/H] -2.5; preliminary tests indicate that a metallicity limit as low as [Fe/H] -3.0 may apply to cooler stars. As a further validation of this approach, weighted averages of [α/Fe] obtained for SEGUE spectra of likely member stars of Galactic globular clusters (M15, M13, and M71) and open clusters (NGC2420, M67, and NGC6791) exhibit good agreement with the values of [α/Fe] from previous studies. The results of the comparison with NGC6791 imply that the metallicity range for the method may extend to +0.5. © 2011. The American Astronomical Society. All rights reserved.
DOI
10.1088/0004-6256/141/3/90
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사범대학 > 과학교육과 > Journal papers
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