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The age, metallicity and α-element abundance of Galactic globular clusters from single stellar population models

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posted on 2024-07-26, 14:45 authored by Jon T. Mendel, Robert N. Proctor, Duncan ForbesDuncan Forbes
Establishing the reliability with which stellar population parameters can be measured is vital to extragalactic astronomy. Galactic globular clusters (GCs) provide an excellent medium in which to test the consistency of single stellar population (SSP) models as they should be our best analogue to a homogeneous (single) stellar population. Here we present age, metallicity and alpha-element abundance measurements for 48 Galactic GCs as determined from integrated spectra using Lick indices and SSP models from Thomas, Maraston & Korn, Lee & Worthey and Vazdekis et al. By comparing our new measurements to independent determinations we are able to assess the ability of these SSPs to derive consistent results - a key requirement before application to heterogeneous stellar populations like galaxies. We find that metallicity determinations are extremely robust, showing good agreement for all models examined here, including a range of enhancement methods. Ages and alpha-element abundances are accurate for a subset of our models, with the caveat that the range of these parameters in Galactic GCs is limited. We are able to show that the application of published Lick index response functions to models with fixed abundance ratios allows us to measure reasonable alpha-element abundances from a variety of models. We also examine the age-metallicity and [alpha/Fe]-metallicity relations predicted by SSP models, and characterize the possible effects of varied model horizontal branch morphology on our overall results.

Funding

Australian Research Council

National Science Foundation

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PDF (Accepted manuscript)

ISSN

0035-8711

Journal title

Monthly Notices of the Royal Astronomical Society

Volume

379

Issue

4

Pagination

18 pp

Publisher

Wiley

Copyright statement

Copyright © 2007 Royal Astronomical Society. The accepted manuscript is reproduced in accordance with the copyright policy of the publisher.

Language

eng

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