THE SEGUE STELLAR PARAMETER PIPELINE. V. ESTIMATION OF ALPHA-ELEMENT ABUNDANCE RATIOS FROM LOW-RESOLUTION SDSS/SEGUE STELLAR SPECTRA

By Y. S. Lee, Timothy C. Beers, C. Allende Prieto, David K. Lai, C. Rockosi, H. Morrison, Jennifer A. Johnson, D. An, T. Sivarani, Brian Yanny. 2010

143 citations recorded by the source corpus.

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 Teff = [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 (NGC 2420, M67, and NGC 6791) exhibit good agreement with the values of [α/Fe] from previous studies. The results of the comparison with NGC 6791 imply that the metallicity range for the method may extend to ∼+0.5.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/3793f68f90746c5d689bcc2e5f1a3cb2508d41f2

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

In Instrumentation

Citations in the corpus

Chemodynamical evolution of the Milky Way disk II: Variations with Galactic radius and height above the disk plane (2014, background): “It should be noted that the gap in [α/Fe] (usually∼ 0.2 dex) has now been seen in a number of different observational samples (e.g., SEGUE - Lee et al. 2011, APOGEE - Anders et al. 2014, HARPS - Adibekyan et al. 2013, GES - Recio-Blanco et al. 2014) indicating that it may be a real feature and not…”
FORMATION AND EVOLUTION OF THE DISK SYSTEM OF THE MILKY WAY: [α/Fe] RATIOS AND KINEMATICS OF THE SEGUE G-DWARF SAMPLE (2011, methodology): “According to Lee et al. (2011), the error in [α/Fe] at S/N = 30 Å−1 is about 0.08 dex.”
The Milky Way’s stellar disk (2013, background): “Such data can provide robust metallicities [Fe/H], good to δ[Fe/H] ≤ 0.2, and constrain [α/Fe] toδ[α/Fe] ≤ 0.15 (Lee et al. 2008a; Lee et al. 2011), for F, G and K stars.”
Extragalactic science, cosmology, and Galactic archaeology with the Subaru Prime Focus Spectrograph (2012, background): “Furthermore, the [α/Fe] ratios are excellent discriminators of the thick disk from the thin disk, with which one can set important limits on the formation scenario of the thick disk by investigating its rotational and orbital properties as a function of [Fe/H] (Lee et al. 2011).”
Empirical extinction coefficients for the GALEX, SDSS, 2MASS and WISE passbands (2013, unknown): “…spectra for over 500 000 stars, along with stellar parameters deduced from the Sloan Extension for Galactic Understanding and Exploration (SEGUE; Yanny et al. 2009) Stellar Parameter Pipeline (SSPP, Lee et al. 2008a,b; Allende Prieto et al. 2008; Lee et al. 2011; Smolinski et al. 2011).”
PROBING THE OUTER GALACTIC HALO WITH RR LYRAE FROM THE CATALINA SURVEYS (2012, methodology): “In contrast to these methods, the SDSS team applied 12 separate methods for determining [Fe/H] in DR8 via the SEGUE pipeline (Lee et al. 2008, 2011).”
CARBON-ENHANCED METAL-POOR STARS IN SDSS/SEGUE. I. CARBON ABUNDANCE ESTIMATION AND FREQUENCY OF CEMP STARS (2013, methodology): “As described by Lee et al. (2011), the SSPP can also obtain an estimate of [α/Fe],16 with a precision of better than 0.1 dex, for SDSS/SEGUE spectra having S/N≥ 20 Å−1.”
HIGH-RESOLUTION SPECTROSCOPY OF EXTREMELY METAL-POOR STARS FROM SDSS/SEGUE. I. ATMOSPHERIC PARAMETERS AND CHEMICAL COMPOSITIONS (2012, background): “See Lee et al. (2008a,b), Allende Prieto et al. (2008), Smolinski et al. (2011), and Lee et al. (2011) for additional discussion of the SSPP.”
THE SPATIAL STRUCTURE OF MONO-ABUNDANCE SUB-POPULATIONS OF THE MILKY WAY DISK (2011, methodology): “Note that our signal-to-noise-ratio cut of SN > 15 is more inclusive than recommended by Lee et al. (2011a) (who recommend SN > 20), but this does not increase the uncertainties in [α/Fe] by much.”
Synthetic stellar photometry – I. General considerations and new transformations for broad-band systems (2014, methodology): “…and synthetic ugriz colours for a sample of about 13500 stars in the SEGUE DR8 catalogue (Yanny et al. 2009), flagged to have good photometric quality in all bands, and to cover a broad range of stellar parameters as determined from the SSPP pipeline (Lee et al. 2011, and references therein).”
A DIRECT DYNAMICAL MEASUREMENT OF THE MILKY WAY'S DISK SURFACE DENSITY PROFILE, DISK SCALE LENGTH, AND DARK MATTER PROFILE AT 4 kpc ≲ R ≲ 9 kpc (2013, background): “For a detailed description of the sample, we refer to BO12d, BO12c, Yanny et al. (2009), and Lee et al. (2011b).”
Gaia FGK benchmark stars: Effective temperatures and surface gravities (2015, methodology): “Eleven of the current Gaia FGK benchmark stars are included in one of the stellar samples that were used to validate the SDSS/SEGUE stellar parameter pipeline by Lee et al. (2011).”
LAMOST Experiment for Galactic Understanding and Exploration (LEGUE) — The survey's science plan (2012, background): “Observational evidence of radial migration has been reported by Yu et al. (2012), Lee et al. (2011), Loebman et al. (2011), Liu & Van de Ven (2012) etc.”
THE METALLICITY DISTRIBUTION FUNCTIONS OF SEGUE G AND K DWARFS: CONSTRAINTS FOR DISK CHEMICAL EVOLUTION AND FORMATION (2011, methodology): “For the overlap region for the G and K dwarfs, i.e., between 1.59 and 1.84 kpc, both spectral types peak at around [Fe/H] of −0.5, consistent with the peak metallicity for the α-enhanced sample identified by Lee et al. (2011b).”