The Case of the Missing Cyanogen-rich AGB Stars in Galactic Globular Clusters

S W Campbell; D Yong; E C Wylie de Boer; R J Stancliffe; J C Lattanzio; G C Angelou; Frank Grundahl; Christopher A Sneden

The Case of the Missing Cyanogen-rich AGB Stars in Galactic Globular Clusters

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

School of Mathematics

Research output: Contribution to conference › Poster

Abstract

The handful of available observations of AGB stars in Galactic Globular Clusters suggest that the GC AGB populations are dominated by cyanogen-weak stars (eg. Norris et al. 1981; Sneden et al. 2000). This contrasts strongly with the distributions on the RGB (and other) populations, which generally show a 50:50 bimodality in CN band strength. If this is a real difference 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 GCs. Our preliminary results indicate there is indeed a lack of CN-strong AGB stars.

Original language	English
Number of pages	2
Publication status	Published - 2012
Event	Conference on the Galactic Archaeology - Near-Field Cosmology and the Formation of the Milky Way - Duration: 1 Jan 2011 → …

Conference

Conference	Conference on the Galactic Archaeology - Near-Field Cosmology and the Formation of the Milky Way
Period	1/01/11 → …

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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. A. (2012). The Case of the Missing Cyanogen-rich AGB Stars in Galactic Globular Clusters. Poster session presented at Conference on the Galactic Archaeology - Near-Field Cosmology and the Formation of the Milky Way. http://aspbooks.org/custom/publications/paper/458-0205.html

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abstract = "The handful of available observations of AGB stars in Galactic Globular Clusters suggest that the GC AGB populations are dominated by cyanogen-weak stars (eg. Norris et al. 1981; Sneden et al. 2000). This contrasts strongly with the distributions on the RGB (and other) populations, which generally show a 50:50 bimodality in CN band strength. If this is a real difference 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 GCs. Our preliminary results indicate there is indeed a lack of CN-strong AGB stars.",

author = "Campbell, {S W} and D Yong and {Wylie de Boer}, {E C} and Stancliffe, {R J} and Lattanzio, {J C} and Angelou, {G C} and Frank Grundahl and Sneden, {Christopher A}",

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T1 - The Case of the Missing Cyanogen-rich AGB Stars in Galactic Globular Clusters

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, Frank

AU - Sneden, Christopher A

PY - 2012

Y1 - 2012

N2 - The handful of available observations of AGB stars in Galactic Globular Clusters suggest that the GC AGB populations are dominated by cyanogen-weak stars (eg. Norris et al. 1981; Sneden et al. 2000). This contrasts strongly with the distributions on the RGB (and other) populations, which generally show a 50:50 bimodality in CN band strength. If this is a real difference 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 GCs. Our preliminary results indicate there is indeed a lack of CN-strong AGB stars.

AB - The handful of available observations of AGB stars in Galactic Globular Clusters suggest that the GC AGB populations are dominated by cyanogen-weak stars (eg. Norris et al. 1981; Sneden et al. 2000). This contrasts strongly with the distributions on the RGB (and other) populations, which generally show a 50:50 bimodality in CN band strength. If this is a real difference 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 GCs. Our preliminary results indicate there is indeed a lack of CN-strong AGB stars.

M3 - Poster

T2 - Conference on the Galactic Archaeology - Near-Field Cosmology and the Formation of the Milky Way

Y2 - 1 January 2011

ER -