Globular cluster abundances: The role of asymptotic giant branch stars

Amanda I. Karakas

doi:10.1017/S1743921309991013

Globular cluster abundances: The role of asymptotic giant branch stars

Amanda I. Karakas^*

^*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceeding › Chapter › peer-review

Abstract

One of the more popular theories to account for the abundance anomalies in globular cluster stars is the 'self-pollution scenario,' where the polluters were a previous generation of intermediate-mass asymptotic giant branch (AGB) stars. This idea has proved attractive because: (i) the hot-bottom burning experienced by these objects qualitatively provides an ideal proton-capture environment to produce helium and convert C and O to N, Ne to Na and Mg to Al, and (ii) the slow winds from these stars allow their retention by the cluster's gravitational potential. New stellar yields from low-metallicity AGB models are presented and compared to abundances derived in globular clusters. We also discuss external pollution and inhomogeneous-pollution models that use AGB stars as polluters. Current models of AGB stars cannot match all observational features of globular cluster stars. However, stellar modelling uncertainties are considerable and suggest AGB stars should not be ruled out just yet.

Original language	English
Title of host publication	Star clusters
Subtitle of host publication	basic galactic building blocks throughout time and space
Editors	Richard de Grijs, Richard de Grijs, Jacques Lepine
Pages	161-168
Number of pages	8
Edition	S266
DOIs	https://doi.org/10.1017/S1743921309991013
Publication status	Published - 2009

Publication series

Name	Proceedings of the International Astronomical Union
Number	S266
Volume	5
ISSN (Print)	1743-9213
ISSN (Electronic)	1743-9221

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10.1017/S1743921309991013

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title = "Globular cluster abundances: The role of asymptotic giant branch stars",

abstract = "One of the more popular theories to account for the abundance anomalies in globular cluster stars is the 'self-pollution scenario,' where the polluters were a previous generation of intermediate-mass asymptotic giant branch (AGB) stars. This idea has proved attractive because: (i) the hot-bottom burning experienced by these objects qualitatively provides an ideal proton-capture environment to produce helium and convert C and O to N, Ne to Na and Mg to Al, and (ii) the slow winds from these stars allow their retention by the cluster's gravitational potential. New stellar yields from low-metallicity AGB models are presented and compared to abundances derived in globular clusters. We also discuss external pollution and inhomogeneous-pollution models that use AGB stars as polluters. Current models of AGB stars cannot match all observational features of globular cluster stars. However, stellar modelling uncertainties are considerable and suggest AGB stars should not be ruled out just yet.",

keywords = "Globular clusters: general, Stars: AGB and post-AGB, Stars: abundances",

author = "Karakas, {Amanda I.}",

year = "2009",

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language = "English",

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series = "Proceedings of the International Astronomical Union",

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editor = "{de Grijs}, Richard and {de Grijs}, Richard and Jacques Lepine",

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edition = "S266",

}

Globular cluster abundances: The role of asymptotic giant branch stars. / Karakas, Amanda I.
Star clusters: basic galactic building blocks throughout time and space. ed. / Richard de Grijs; Richard de Grijs; Jacques Lepine. S266. ed. 2009. p. 161-168 (Proceedings of the International Astronomical Union; Vol. 5, No. S266).

Research output: Chapter in Book/Report/Conference proceeding › Chapter › peer-review

TY - CHAP

T1 - Globular cluster abundances

T2 - The role of asymptotic giant branch stars

AU - Karakas, Amanda I.

PY - 2009

Y1 - 2009

N2 - One of the more popular theories to account for the abundance anomalies in globular cluster stars is the 'self-pollution scenario,' where the polluters were a previous generation of intermediate-mass asymptotic giant branch (AGB) stars. This idea has proved attractive because: (i) the hot-bottom burning experienced by these objects qualitatively provides an ideal proton-capture environment to produce helium and convert C and O to N, Ne to Na and Mg to Al, and (ii) the slow winds from these stars allow their retention by the cluster's gravitational potential. New stellar yields from low-metallicity AGB models are presented and compared to abundances derived in globular clusters. We also discuss external pollution and inhomogeneous-pollution models that use AGB stars as polluters. Current models of AGB stars cannot match all observational features of globular cluster stars. However, stellar modelling uncertainties are considerable and suggest AGB stars should not be ruled out just yet.

AB - One of the more popular theories to account for the abundance anomalies in globular cluster stars is the 'self-pollution scenario,' where the polluters were a previous generation of intermediate-mass asymptotic giant branch (AGB) stars. This idea has proved attractive because: (i) the hot-bottom burning experienced by these objects qualitatively provides an ideal proton-capture environment to produce helium and convert C and O to N, Ne to Na and Mg to Al, and (ii) the slow winds from these stars allow their retention by the cluster's gravitational potential. New stellar yields from low-metallicity AGB models are presented and compared to abundances derived in globular clusters. We also discuss external pollution and inhomogeneous-pollution models that use AGB stars as polluters. Current models of AGB stars cannot match all observational features of globular cluster stars. However, stellar modelling uncertainties are considerable and suggest AGB stars should not be ruled out just yet.

KW - Globular clusters: general

KW - Stars: AGB and post-AGB

KW - Stars: abundances

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U2 - 10.1017/S1743921309991013

DO - 10.1017/S1743921309991013

M3 - Chapter

SN - 9780521764995

T3 - Proceedings of the International Astronomical Union

SP - 161

EP - 168

BT - Star clusters

A2 - de Grijs, Richard

A2 - Lepine, Jacques

ER -

Globular cluster abundances: The role of asymptotic giant branch stars

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