Light‐Element Abundance Variations in Globular Clusters

Martell, Sarah L.

doi:10.1002/9783527644384.ch10

Cited by 4 publications

(2 citation statements)

References 93 publications

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“…1G stars show primordial (oxygen-rich, sodium-poor) chemical composition similar to that of field stars (e.g. Martell 2011). Elemental abundance patterns of 2G stars are ascribed by CNO cycling and p-capture processes at high temperatures (e.g.…”

Section: Introductionmentioning

confidence: 97%

Simulations of globular clusters within their parent galaxies: multiple stellar populations and internal kinematics

McKenzie,

Bekki

2021

Preprint

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Using three-dimensional smoothed particle hydrodynamics simulations, we investigate the formation of multiple stellar populations (MSPs) in globular clusters (GCs) within the context of their parent galaxies. In our scenario, the second generation (2G) of stars originate from both asymptotic giant branch (AGB) polluters and pristine gas accreted from the host galaxy. Previous theoretical and numerical studies have demonstrated that this "AGB with dilution" model has the potential to alleviate several problems faced by the classical AGB scenario. However, the accretion of pristine gas onto the GC has yet to be investigated within the context of the parent galaxy. This paper presents the preliminary results from our original simulation code which models GC formation from giant molecular clouds in a host galaxy, and subsequent gas accretion onto the GC. By simulating the genesis of the 2G over a 370 Myr time frame, we demonstrate that the fraction of 2G stars is inextricably linked to the GC's environment. Our simulations rationalise the wide variety of abundance patterns, kinematics and 2G concentrations by altering the initial conditions of both the GC progenitor and the host galaxy itself. Most notably, we reproduce a positive correlation between the fraction of 2G stars and the initial mass of the cluster. We discuss the physical implications of our scenario and compare our simulations with observations of the Galactic GC 47 Tucanae (47 Tuc). Finally, we present scaling relations which encompass the wider GC population and serve as a reference for future observations.

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Section: Introductionmentioning

confidence: 97%

Simulations of globular clusters within their parent galaxies: multiple stellar populations and internal kinematics

McKenzie,

Bekki

2021

Preprint

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“…First generation stars (hereafter 1G stars, nomenclature adopted from Piotto et al 2015) posses chemical signatures similar to that of field stars (e.g. Martell 2011). Second generation or 2G stars exhibit chemical compositions produced by CNO cycling and p-capture processes at high temperatures (e.g.…”

Section: Introductionmentioning

confidence: 99%

Simulations of globular clusters within their parent galaxies: Metallicity spreads and anomalous precursor populations

McKenzie,

Bekki

2021

Preprint

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Recent observations of globular clusters (GCs) suggest that elemental abundance variations may exist between first-generation (1G) stars. We propose that metal abundance ('metallicity') spreads within GC forming giant molecular clouds (GMCs) can influence the iron abundances of future cluster members. To investigate this, we use original hydrodynamical simulations to model GMC formation in a high redshift dwarf galaxy. Our simulations self-consistently model physical processes such as stellar feedback, dust formation and destruction, and molecular gas formation on dust grains, making them well suited to the study of GMC formation. We conclude that iron abundance variations in GMCs are due to the merging of gas clumps and self-enrichment processes. The metallicity dispersions of GC forming clumps is ∼0.1 dex, reflecting a growing number of studies that claim a non-zero dispersion within GCs. The galactic gas fraction is a key parameter for the formation of clumps and the metallicity 'floor' observed for both Galactic and extra-galactic GCs are associated with the parent galaxy's capacity to form massive GMCs. Finally, we argue that GMCs have the potential to trap surrounding metal-poor galactic disc stars, which we interpret as a precursor population (0G). These low metallicity stars are representative of the [Fe/H] value of the host dwarf and thus the chemistry of this 0G may be a fossilised record of the parent galaxy. These results depend on the initial metallicity and radial gradient of the galaxy, the threshold gas density for star formation and the star formation prescription.

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Simulations of globular clusters within their parent galaxies: multiple stellar populations and internal kinematics

McKenzie

Bekki

2020

Monthly Notices of the Royal Astronomical Society

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Using three-dimensional smoothed particle hydrodynamical simulations, we investigate the formation of multiple stellar populations (MSPs) in globular clusters (GCs) within the context of their parent galaxies. In our scenario, the second generation of stars (2G) originate from both asymptotic giant branch (AGB) polluters and pristine gas accreted from the host galaxy. Previous theoretical and numerical studies have demonstrated that this “AGB with dilution” model has the potential to alleviate several problems faced by the classical AGB scenario. However, the accretion of pristine gas onto the GC has yet to be investigated within the context of the parent galaxy. This paper presents the preliminary results from our original simulation code which models GC formation from giant molecular clouds in a host galaxy, and subsequent gas accretion onto the GC. By simulating the genesis of the 2G over a 370 Myr time frame, we demonstrate that the fraction of 2G stars is inextricably linked to the GC’s environment. Our simulations rationalise the wide variety of abundance patterns, kinematics and 2G concentrations by altering the initial conditions of both the GC progenitor and the host galaxy itself. Most notably, we reproduce a positive correlation between the fraction of 2G stars and the initial mass of the cluster. We discuss the physical implications of our scenario and compare our simulations with observations of the Galactic GC 47 Tucanae (47 Tuc). Finally, we present scaling relations which encompass the wider GC population and serve as a reference for future observations.

show abstract

Light‐Element Abundance Variations in Globular Clusters

Cited by 4 publications

References 93 publications

Simulations of globular clusters within their parent galaxies: multiple stellar populations and internal kinematics

Simulations of globular clusters within their parent galaxies: multiple stellar populations and internal kinematics

Simulations of globular clusters within their parent galaxies: Metallicity spreads and anomalous precursor populations

Simulations of globular clusters within their parent galaxies: multiple stellar populations and internal kinematics

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