7 papers
A New Population of Old Stars
I. I. Ivans, C. Sneden, C. R. James +5
We report the results of a coherent study of three chemically anomalous metal-poor ([Fe/H] ~ -2) stars. These objects exhibit unusually low abundances of Mg, Si, Ca (alpha-elements…
A New Globular Cluster Metallicity Scale Based on the Abundance of FeII
R. P. Kraft, I. I. Ivans
When using Fe as a surrogate for ``metallicity'', the metallicity is best represented by the dominant species of Fe. Accordingly, we have derived a new globular cluster metallicity…
Galaxy Mergers: A Search for Chemical Signatures
Inese I. Ivans, Bruce Carney, Luisa de Almeida +1
We have gathered high resolution echelle spectra for more than two dozen high-velocity metal-poor field stars, including BD+80 245, a star previously known to have extremely low [a…
Getting the Red Out: A Stellar Approach to Determining Spatial Variations of Interstellar Dust
I. I. Ivans, C. Sneden, R. P. Kraft +4
By employing two different spectroscopic techniques we have mapped out the variable ISM dust extinction endemic to globular cluster M4. We derive an average E(B-V) reddening of 0.3…
Do AGB Stars Differ Chemically from RGB Stars in Globular Clusters?
Christopher Sneden, Inese I. Ivans, Robert P. Kraft
Recent improvements in globular cluster colour-magnitude diagrams, coupled with an increase in large-sample spectroscopic abundance studies of cluster giants, finally allow some at…
Chemical Abundances of Bright Giants in the Mildly Metal-Poor Globular Cluster M4
Inese I. Ivans
We present a chemical composition analysis of three dozen giant stars in the nearby ``CN-bimodal'' mildly metal-poor (<[Fe/H]> = -1.18) globular cluster M4. The analysis combined t…