AGB subpopulations in the nearby globular cluster NGC6397

B. T. MacLean*, S. W. Campbell, G. M. De Silva, J. Lattanzio, V. D'Orazi, P. L. Cottrell, Y. Momany, L. Casagrande

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    8 Citations (Scopus)

    Abstract

    It has been well established that Galactic Globular clusters (GCs) harbour more than one stellar population, distinguishable by the anticorrelations of light-element abundances (C-N, Na-O, and Mg-Al). These studies have been extended recently to the asymptotic giant branch (AGB). Here, we investigate the AGB of NGC6397 for the first time. We have performed an abundance analysis of high-resolution spectra of 47 red giant branch (RGB) and eight AGB stars, deriving Fe, Na, O, Mg, and Al abundances. We find that NGC6397 shows no evidence of a deficit in Na-rich AGB stars, as reported for some other GCs - the subpopulation ratios of the AGB and RGB in NGC6397 are identical, within uncertainties. This agrees with expectations from stellar theory. This GC acts as a control for our earlier work on the AGB of M4 (with contrasting results), since the same tools and methods were used.

    Original languageEnglish
    Article numberstx3217
    Pages (from-to)257-265
    Number of pages9
    JournalMonthly Notices of the Royal Astronomical Society
    Volume475
    Issue number1
    DOIs
    Publication statusPublished - 21 Mar 2018

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