AGB Stars in Galactic Globular Clusters: Are They Really Chemically Distinct from Their Fellow RGB and HB Stars?

S W Campbell, D Yong, E C Wylie de Boer, R J Stancliffe, J C Lattanzio, G C Angelou, F Grundahl, C Sneden

Research output: Chapter in Book/Report/Conference proceedingConference PaperResearch


The handful of available observations of asymptotic giant branch (AGB) stars in Galactic globular clusters (GCs) suggest that the globular cluster AGB populations are dominated by cyanogen-weak (CN-weak) stars. This contrasts strongly with the distributions on the red giant branch (RGB) and other populations, which often show a 50:50 bimodality in CN band strength. If this is true then it presents a serious problem for low metallicity stellar evolution theory, since such a surface abundance change going from the RGB to AGB is not predicted by stellar models. However this is only a tentative conclusion, since it is based on very small AGB sample sizes. To test whether this problem really exists we have carried out an observational campaign targeting AGB stars in globular clusters. We have obtained medium resolution spectra for about 250 AGB stars across 9 Galactic globular clusters (NGC 1851, NGC 288, NGC 362, NGC 6752, M2, M4, M5, M10, and 47 Tuc) using the multi-object spectrograph on the Anglo-Australian Telescope (2df/AAOmega). In this contribution we present some preliminary findings of the study, in particular for the second-parameter pair NGC 288 and NGC 362.
Original languageEnglish
Title of host publicationWhy galaxies care about AGB starts II: Shining examples and common inhabitants
Subtitle of host publicationProceedings of a conference held at University Campus, Vienna, Austria 16-20 August 2010
EditorsF Kerschbaum, T Lebzelter, R F Wing
Place of PublicationSan Francisco CA USA
PublisherAstronomical Society of the Pacific
Number of pages6
ISBN (Electronic)9781583817711
ISBN (Print)9781583817704
Publication statusPublished - 2011
EventConference on Why Galaxies Care About AGB Stars II (2010): Shining Examples and Common Inhabitants - University Campus, Vienna, Vienna, Austria
Duration: 16 Aug 201020 Aug 2010

Publication series

NameAstronomical Society of the Pacific Conference Series
PublisherAstronomical Society of the Pacific


ConferenceConference on Why Galaxies Care About AGB Stars II (2010)

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