GLOBULAR CLUSTER ABUNDANCES FROM HIGH-RESOLUTION, INTEGRATED-LIGHT SPECTROSCOPY. II. EXPANDING THE METALLICITY RANGE FOR OLD CLUSTERS AND UPDATED ANALYSIS TECHNIQUES

• Published in: The Astrophysical journal Vol. 834; no. 2; p. 105
• Main Authors: Colucci, Janet E., Bernstein, Rebecca A., McWilliam, Andrew
• Format: Journal Article
• Language: English
• Published: Philadelphia IOP Publishing 10.01.2017
• Subjects: Abundance; ACCURACY; Aluminum; Astrophysics; ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; Barium; Calcium; Cluster analysis; Copper; ELEMENT ABUNDANCE; EVALUATION; Globular clusters; HYDROGEN; IRON; MAGNESIUM; Manganese; METALLICITY; MILKY WAY; NEODYMIUM; Nickel; RESOLUTION; SCANDIUM; Silicon; SODIUM; Spectroscopy; Spectrum analysis; STAR CLUSTERS; STARS; Stellar spectra; TITANIUM; VISIBLE RADIATION; ZIRCONIUM
• ISSN: 0004-637X; 1538-4357
• DOI: 10.3847/1538-4357/834/2/105

ABSTRACT We present abundances of globular clusters (GCs) in the Milky Way and Fornax from integrated-light (IL) spectra. Our goal is to evaluate the consistency of the IL analysis relative to standard abundance analysis for individual stars in those same clusters. This sample includes an updated analysis of seven clusters from our previous publications and results for five new clusters that expand the metallicity range over which our technique has been tested. We find that the [Fe/H] measured from IL spectra agrees to ∼0.1 dex for GCs with metallicities as high as [Fe/H] = −0.3, but the abundances measured for more metal-rich clusters may be underestimated. In addition we systematically evaluate the accuracy of abundance ratios, [X/Fe], for Na i , Mg i , Al i , Si i , Ca i , Ti i , Ti ii , Sc ii , V i , Cr i , Mn i , Co i , Ni i , Cu i , Y ii , Zr i , Ba ii , La ii , Nd ii , and Eu ii . The elements for which the IL analysis gives results that are most similar to analysis of individual stellar spectra are Fe i , Ca i , Si i , Ni i , and Ba ii . The elements that show the greatest differences include Mg i and Zr i . Some elements show good agreement only over a limited range in metallicity. More stellar abundance data in these clusters would enable more complete evaluation of the IL results for other important elements.