Sodium content as a predictor of the advanced evolution of globular cluster stars

Simon W. Campbell; Valentina D'Orazi; David Yong; Thomas N. Constantino; John C. Lattanzio; Richard J. Stancliffe; George C. Angelou; Elizabeth C. Wylie-De Boer; Frank Grundahl

doi:10.1038/nature12191

Sodium content as a predictor of the advanced evolution of globular cluster stars

Simon W. Campbell^*, Valentina D'Orazi, David Yong, Thomas N. Constantino, John C. Lattanzio, Richard J. Stancliffe, George C. Angelou, Elizabeth C. Wylie-De Boer, Frank Grundahl

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

73 Citations (Scopus)

Abstract

The asymptotic giant branch (AGB) phase is the final stage of nuclear burning for low-mass stars. Although Milky Way globular clusters are now known to harbour (at least) two generations of stars, they still provide relatively homogeneous samples of stars that are used to constrain stellar evolution theory. It is predicted by stellar models that the majority of cluster stars with masses around the current turn-off mass (that is, the mass of the stars that are currently leaving the main sequence phase) will evolve through the AGB phase. Here we report that all of the second-generation stars in the globular cluster NGC 6752 - 70 per cent of the cluster population - fail to reach the AGB phase. Through spectroscopic abundance measurements, we found that every AGB star in our sample has a low sodium abundance, indicating that they are exclusively first-generation stars. This implies that many clusters cannot reliably be used for star counts to test stellar evolution timescales if the AGB population is included. We have no clear explanation for this observation.

Original language	English
Pages (from-to)	198-200
Number of pages	3
Journal	Nature
Volume	498
Issue number	7453
DOIs	https://doi.org/10.1038/nature12191
Publication status	Published - 2013

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@article{b95663b7864f4f4fb107285bc955fbd3,

title = "Sodium content as a predictor of the advanced evolution of globular cluster stars",

abstract = "The asymptotic giant branch (AGB) phase is the final stage of nuclear burning for low-mass stars. Although Milky Way globular clusters are now known to harbour (at least) two generations of stars, they still provide relatively homogeneous samples of stars that are used to constrain stellar evolution theory. It is predicted by stellar models that the majority of cluster stars with masses around the current turn-off mass (that is, the mass of the stars that are currently leaving the main sequence phase) will evolve through the AGB phase. Here we report that all of the second-generation stars in the globular cluster NGC 6752 - 70 per cent of the cluster population - fail to reach the AGB phase. Through spectroscopic abundance measurements, we found that every AGB star in our sample has a low sodium abundance, indicating that they are exclusively first-generation stars. This implies that many clusters cannot reliably be used for star counts to test stellar evolution timescales if the AGB population is included. We have no clear explanation for this observation.",

author = "Campbell, {Simon W.} and Valentina D'Orazi and David Yong and Constantino, {Thomas N.} and Lattanzio, {John C.} and Stancliffe, {Richard J.} and Angelou, {George C.} and {Wylie-De Boer}, {Elizabeth C.} and Frank Grundahl",

year = "2013",

doi = "10.1038/nature12191",

language = "English",

volume = "498",

pages = "198--200",

journal = "Nature",

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T1 - Sodium content as a predictor of the advanced evolution of globular cluster stars

AU - Campbell, Simon W.

AU - D'Orazi, Valentina

AU - Yong, David

AU - Constantino, Thomas N.

AU - Lattanzio, John C.

AU - Stancliffe, Richard J.

AU - Angelou, George C.

AU - Wylie-De Boer, Elizabeth C.

AU - Grundahl, Frank

PY - 2013

Y1 - 2013

N2 - The asymptotic giant branch (AGB) phase is the final stage of nuclear burning for low-mass stars. Although Milky Way globular clusters are now known to harbour (at least) two generations of stars, they still provide relatively homogeneous samples of stars that are used to constrain stellar evolution theory. It is predicted by stellar models that the majority of cluster stars with masses around the current turn-off mass (that is, the mass of the stars that are currently leaving the main sequence phase) will evolve through the AGB phase. Here we report that all of the second-generation stars in the globular cluster NGC 6752 - 70 per cent of the cluster population - fail to reach the AGB phase. Through spectroscopic abundance measurements, we found that every AGB star in our sample has a low sodium abundance, indicating that they are exclusively first-generation stars. This implies that many clusters cannot reliably be used for star counts to test stellar evolution timescales if the AGB population is included. We have no clear explanation for this observation.

AB - The asymptotic giant branch (AGB) phase is the final stage of nuclear burning for low-mass stars. Although Milky Way globular clusters are now known to harbour (at least) two generations of stars, they still provide relatively homogeneous samples of stars that are used to constrain stellar evolution theory. It is predicted by stellar models that the majority of cluster stars with masses around the current turn-off mass (that is, the mass of the stars that are currently leaving the main sequence phase) will evolve through the AGB phase. Here we report that all of the second-generation stars in the globular cluster NGC 6752 - 70 per cent of the cluster population - fail to reach the AGB phase. Through spectroscopic abundance measurements, we found that every AGB star in our sample has a low sodium abundance, indicating that they are exclusively first-generation stars. This implies that many clusters cannot reliably be used for star counts to test stellar evolution timescales if the AGB population is included. We have no clear explanation for this observation.

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U2 - 10.1038/nature12191

DO - 10.1038/nature12191

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SN - 0028-0836

VL - 498

SP - 198

EP - 200

JO - Nature

JF - Nature

IS - 7453

ER -

Sodium content as a predictor of the advanced evolution of globular cluster stars

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