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

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 proceeding › Conference Paper › Research

Abstract

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 language	English
Title of host publication	Why galaxies care about AGB starts II: Shining examples and common inhabitants
Subtitle of host publication	Proceedings of a conference held at University Campus, Vienna, Austria 16-20 August 2010
Editors	F Kerschbaum, T Lebzelter, R F Wing
Place of Publication	San Francisco CA USA
Publisher	Astronomical Society of the Pacific
Pages	63-68
Number of pages	6
Volume	445
Edition	1
ISBN (Electronic)	9781583817711
ISBN (Print)	9781583817704
Publication status	Published - 2011
Event	Conference on Why Galaxies Care About AGB Stars II (2010): Shining Examples and Common Inhabitants - University Campus, Vienna, Vienna, Austria Duration: 16 Aug 2010 → 20 Aug 2010

Publication series

Name	Astronomical Society of the Pacific Conference Series
Publisher	Astronomical Society of the Pacific
Volume	445

Conference

Conference	Conference on Why Galaxies Care About AGB Stars II (2010)
Country/Territory	Austria
City	Vienna
Period	16/08/10 → 20/08/10

Access to Document

244224716-oaFinal published version, 303 KB

http://aspbooks.org/custom/publications/paper/445-0063.html

Cite this

Campbell, S. W., Yong, D., Wylie de Boer, E. C., Stancliffe, R. J., Lattanzio, J. C., Angelou, G. C., Grundahl, F., & Sneden, C. (2011). AGB Stars in Galactic Globular Clusters: Are They Really Chemically Distinct from Their Fellow RGB and HB Stars? In F. Kerschbaum, T. Lebzelter, & R. F. Wing (Eds.), Why galaxies care about AGB starts II: Shining examples and common inhabitants: Proceedings of a conference held at University Campus, Vienna, Austria 16-20 August 2010 (1 ed., Vol. 445, pp. 63-68). (Astronomical Society of the Pacific Conference Series; Vol. 445). Astronomical Society of the Pacific. http://aspbooks.org/custom/publications/paper/445-0063.html

Campbell, S W ; Yong, D ; Wylie de Boer, E C et al. / AGB Stars in Galactic Globular Clusters : Are They Really Chemically Distinct from Their Fellow RGB and HB Stars?. Why galaxies care about AGB starts II: Shining examples and common inhabitants: Proceedings of a conference held at University Campus, Vienna, Austria 16-20 August 2010. editor / F Kerschbaum ; T Lebzelter ; R F Wing. Vol. 445 1. ed. San Francisco CA USA : Astronomical Society of the Pacific, 2011. pp. 63-68 (Astronomical Society of the Pacific Conference Series).

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

abstract = "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.",

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Campbell, SW, Yong, D, Wylie de Boer, EC, Stancliffe, RJ, Lattanzio, JC, Angelou, GC, Grundahl, F & Sneden, C 2011, AGB Stars in Galactic Globular Clusters: Are They Really Chemically Distinct from Their Fellow RGB and HB Stars? in F Kerschbaum, T Lebzelter & RF Wing (eds), Why galaxies care about AGB starts II: Shining examples and common inhabitants: Proceedings of a conference held at University Campus, Vienna, Austria 16-20 August 2010. 1 edn, vol. 445, Astronomical Society of the Pacific Conference Series, vol. 445, Astronomical Society of the Pacific, San Francisco CA USA, pp. 63-68, Conference on Why Galaxies Care About AGB Stars II (2010), Vienna, Austria, 16/08/10. <http://aspbooks.org/custom/publications/paper/445-0063.html>

AGB Stars in Galactic Globular Clusters : Are They Really Chemically Distinct from Their Fellow RGB and HB Stars? / Campbell, S W; Yong, D; Wylie de Boer, E C et al.

Why galaxies care about AGB starts II: Shining examples and common inhabitants: Proceedings of a conference held at University Campus, Vienna, Austria 16-20 August 2010. ed. / F Kerschbaum; T Lebzelter; R F Wing. Vol. 445 1. ed. San Francisco CA USA : Astronomical Society of the Pacific, 2011. p. 63-68 (Astronomical Society of the Pacific Conference Series; Vol. 445).

Research output: Chapter in Book/Report/Conference proceeding › Conference Paper › Research

TY - GEN

T1 - AGB Stars in Galactic Globular Clusters

T2 - Conference on Why Galaxies Care About AGB Stars II (2010)

AU - Campbell, S W

AU - Yong, D

AU - Wylie de Boer, E C

AU - Stancliffe, R J

AU - Lattanzio, J C

AU - Angelou, G C

AU - Grundahl, F

AU - Sneden, C

PY - 2011

Y1 - 2011

N2 - 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.

AB - 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.

M3 - Conference Paper

SN - 9781583817704

VL - 445

T3 - Astronomical Society of the Pacific Conference Series

SP - 63

EP - 68

BT - Why galaxies care about AGB starts II: Shining examples and common inhabitants

A2 - Kerschbaum, F

A2 - Lebzelter, T

A2 - Wing, R F

PB - Astronomical Society of the Pacific

CY - San Francisco CA USA

Y2 - 16 August 2010 through 20 August 2010

ER -

Campbell SW, Yong D, Wylie de Boer EC, Stancliffe RJ, Lattanzio JC, Angelou GC et al. AGB Stars in Galactic Globular Clusters: Are They Really Chemically Distinct from Their Fellow RGB and HB Stars? In Kerschbaum F, Lebzelter T, Wing RF, editors, Why galaxies care about AGB starts II: Shining examples and common inhabitants: Proceedings of a conference held at University Campus, Vienna, Austria 16-20 August 2010. 1 ed. Vol. 445. San Francisco CA USA: Astronomical Society of the Pacific. 2011. p. 63-68. (Astronomical Society of the Pacific Conference Series).