A differential chemical abundance scale for the globular cluster M5

Koch, Andreas and McWilliam, Andrew (2010) A differential chemical abundance scale for the globular cluster M5. The Astronomical Journal, 139 (6). pp. 2289-2299. ISSN 0004-6256

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Abstract

We present LTE chemical abundances for five red giants and one AGB star in the Galactic globular cluster (GC) M5 based on high-resolution spectroscopy using the Magellan Inamori Kyocera Echelle spectrograph on the Magellan 6.5 m Clay telescope. Our results are based on a line-by-line differential abundance analysis relative to the well-studied red giant Arcturus. The stars in our sample that overlap with existing studies in the literature are consistent with published values for [Fe/H] and agree to within typically 0.04 dex for the α-elements. Most deviations can be assigned to varying analysis techniques in the literature. This strengthens our newly established differential GC abundance scale and advocates future use of this method. In particular, we confirm a mean [Fe I/H] of –1.33 ± 0.03 (stat.) ±0.03 (sys.) dex and also reproduce M5's enhancement in the α-elements (O, Mg, Si, Ca, Ti) at +0.4 dex, rendering M5 a typical representative of the Galactic halo. Over-ionization of Fe I in the atmospheres of these stars by non-LTE effects is found to be less than 0.07 dex. Five of our six stars show O-Na-Al-Mg abundance patterns consistent with pollution by proton-capture nucleosynthesis products.

Item Type:
Journal Article
Journal or Publication Title:
The Astronomical Journal
Uncontrolled Keywords:
/dk/atira/pure/subjectarea/asjc/1900/1912
Subjects:
ID Code:
83399
Deposited By:
Deposited On:
02 Dec 2016 15:16
Refereed?:
Yes
Published?:
Published
Last Modified:
01 Jan 2020 10:06