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

Research output: Contribution to journalArticleResearchpeer-review

5 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

Keywords

  • Galaxy: abundances
  • Galaxy: formation
  • Globular clusters: general
  • Stars: abundances
  • Stars: AGB and post-AGB

Cite this

MacLean, B. T., Campbell, S. W., De Silva, G. M., Lattanzio, J., D'Orazi, V., Cottrell, P. L., ... Casagrande, L. (2018). AGB subpopulations in the nearby globular cluster NGC6397. Monthly Notices of the Royal Astronomical Society, 475(1), 257-265. [stx3217]. https://doi.org/10.1093/mnras/stx3217
MacLean, B. T. ; Campbell, S. W. ; De Silva, G. M. ; Lattanzio, J. ; D'Orazi, V. ; Cottrell, P. L. ; Momany, Y. ; Casagrande, L. / AGB subpopulations in the nearby globular cluster NGC6397. In: Monthly Notices of the Royal Astronomical Society. 2018 ; Vol. 475, No. 1. pp. 257-265.
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MacLean, BT, Campbell, SW, De Silva, GM, Lattanzio, J, D'Orazi, V, Cottrell, PL, Momany, Y & Casagrande, L 2018, 'AGB subpopulations in the nearby globular cluster NGC6397', Monthly Notices of the Royal Astronomical Society, vol. 475, no. 1, stx3217, pp. 257-265. https://doi.org/10.1093/mnras/stx3217

AGB subpopulations in the nearby globular cluster NGC6397. / MacLean, B. T.; Campbell, S. W.; De Silva, G. M.; Lattanzio, J.; D'Orazi, V.; Cottrell, P. L.; Momany, Y.; Casagrande, L.

In: Monthly Notices of the Royal Astronomical Society, Vol. 475, No. 1, stx3217, 21.03.2018, p. 257-265.

Research output: Contribution to journalArticleResearchpeer-review

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T1 - AGB subpopulations in the nearby globular cluster NGC6397

AU - MacLean, B. T.

AU - Campbell, S. W.

AU - De Silva, G. M.

AU - Lattanzio, J.

AU - D'Orazi, V.

AU - Cottrell, P. L.

AU - Momany, Y.

AU - Casagrande, L.

PY - 2018/3/21

Y1 - 2018/3/21

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AB - 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.

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KW - Galaxy: formation

KW - Globular clusters: general

KW - Stars: abundances

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