A SEARCH FOR STARS OF VERY LOW METAL ABUNDANCE. VI. DETAILED ABUNDANCES OF 313 METAL-POOR STARS

By I. Roederer, G. Preston, I. Thompson, S. Shectman, C. Sneden, G. Burley, D. Kelson. 2014

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We present radial velocities, equivalent widths, model atmosphere parameters, and abundances or upper limits for 53 species of 48 elements derived from high resolution optical spectroscopy of 313 metal-poor stars. A majority of these stars were selected from the metal-poor candidates of the HK Survey of Beers, Preston, and Shectman. We derive detailed abundances for 61% of these stars for the first time. Spectra were obtained during a 10 yr observing campaign using the Magellan Inamori Kyocera Echelle spectrograph on the Magellan Telescopes at Las Campanas Observatory, the Robert G. Tull Coudé Spectrograph on the Harlan J. Smith Telescope at McDonald Observatory, and the High Resolution Spectrograph on the Hobby–Eberly Telescope at McDonald Observatory. We perform a standard LTE abundance analysis using MARCS model atmospheres, and we apply line-by-line statistical corrections to minimize systematic abundance differences arising when different sets of lines are available for analysis. We identify several abundance correlations with effective temperature. A comparison with previous abundance analyses reveals significant differences in stellar parameters, which we investigate in detail. Our metallicities are, on average, lower by ≈0.25 dex for red giants and ≈0.04 dex for subgiants. Our sample contains 19 stars with [Fe/H] ⩽−3.5, 84 stars with [Fe/H] ⩽−3.0, and 210 stars with [Fe/H] ⩽−2.5. Detailed abundances are presented here or elsewhere for 91% of the 209 stars with [Fe/H] ⩽−2.5 as estimated from medium resolution spectroscopy by Beers, Preston, and Shectman. We will discuss the interpretation of these abundances in subsequent papers.

Subfields: Astronomy and Astrophysics, Computational Mechanics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/438e90f48db42ebce6698f344a943b83214bfda6

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Citations in the corpus

Near-Field Cosmology with Extremely Metal-Poor Stars (2015, background): “…abundances for a significant number of stars ( ∼ > 15) having [Fe/H] less than this limit: McWilliam et al. (1995), Ryan, Norris & Beers (1996), Cayrel et al. (2004), Lai et al. (2008 Hollek et al. (2011), Bonifacio et al. (2012b), Yong et al. (2013a), Cohen et al. (2013), Roederer et al. (2014).”
THE HISTORY OF R-PROCESS ENRICHMENT IN THE MILKY WAY (2014, methodology): “For comparison, we overplot [α/Fe] measurements for a sample of Milky Way thin disk, thick disk, and halo stars (see Figure 14 from Sneden, Cowan, & Gallino 2008, with additional stars from Venn et al. 2004, Mishenina et al. 2013, and Roederer et al. 2014).”
DETAILED CHEMICAL ABUNDANCES IN THE r-PROCESS-RICH ULTRA-FAINT DWARF GALAXY RETICULUM 2 (2016, methodology): “…showed that the EWs measured from M2FS HiRes spectra taken with the same 95 µm entrance slits agree to better than 1 mÅ with those derived from MIKE spectra, which were shown by Bedell et al. (2014) and Roederer et al. (2014b) to agree with high-resolution spectra taken at several observatories.”
Chemical evolution with rotating massive star yields - I. The solar neighbourhood and the s-process elements (2018, background): “G A ] 2004; Frebel 2010; Yong et al. 2013; Roederer et al. 2014) confirmed the constantly high [α/Fe] ratio in low metallicities, and revealed a small dispersion for element ratios [X/Fe] up to the Fe-peak and the presence of a large dispersion in that ratio for heavier than Fe elements.”
THE RADIAL VELOCITY EXPERIMENT (RAVE): FIFTH DATA RELEASE (2013, result): “…star surveys We have matched RAVE stars with the high-resolution studies of Gratton et al. (2000); Carrera et al. (2013); Ishigaki et al. (2013); Roederer et al. (2014) and Schlaufman & Casey (2014), which concentrate on bright metalpoor stars, the study of Trevisan et al. (2011), which…”