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

Young Sun Lee, Timothy C. Beers, Carlos Allende Prieto, David K. Lai, Constance M. Rockosi, Heather L. Morrison, Jennifer A. Johnson, Deokkeun An, Thirupathi Sivarani, Brian Yanny

Research output: Contribution to journalArticlepeer-review

111 Scopus citations

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.

Original languageEnglish
Article number90
JournalAstronomical Journal
Volume141
Issue number3
DOIs
StatePublished - Mar 2011

Keywords

  • methods: data analysis
  • stars: abundances
  • stars: fundamental parameters
  • surveys
  • techniques: imaging spectroscopy

Fingerprint

Dive into the research topics of 'The SEGUE stellar parameter Pipeline. V. estimation of alpha-element abundance ratios from low-resolution SDSS/SEGUE stellar spectra'. Together they form a unique fingerprint.

Cite this