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Bayesian analysis of two stellar populations in Galactic globular clusters III: Analysis of 30 clusters

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Title: Bayesian analysis of two stellar populations in Galactic globular clusters III: Analysis of 30 clusters
Authors: Wagner-Kaiser, R
Stenning, D
Sarajedini, A
Von Hippel, T
Van Dyk, DA
Robinson, E
Stein, NM
Jefferys, W
Item Type: Journal Article
Abstract: We use Cycle 21 Hubble Space Telescope (HST) observations and HST archival ACS Treasury observations of 30 Galactic Globular Clusters to characterize two distinct stellar populations. A sophisticated Bayesian technique is employed to simultaneously sample the joint posterior distribution of age, distance, and extinction for each cluster, as well as unique helium values for two populations within each cluster and the relative proportion of those populations. We find the helium differences among the two populations in the clusters fall in the range of ∼0.04 to 0.11. Because adequate models varying in CNO are not presently available, we view these spreads as upper limits and present them with statistical rather than observational uncertainties. Evidence supports previous studies suggesting an increase in helium content concurrent with increasing mass of the cluster and also find that the proportion of the first population of stars increases with mass as well. Our results are examined in the context of proposed globular cluster formation scenarios. Additionally, we leverage our Bayesian technique to shed light on inconsistencies between the theoretical models and the observed data.
Issue Date: 7-Sep-2016
Date of Acceptance: 5-Sep-2016
URI: http://hdl.handle.net/10044/1/39891
DOI: https://dx.doi.org/10.1093/mnras/stw2247
ISSN: 1365-2966
Publisher: Oxford University Press (OUP)
Start Page: 3768
End Page: 3782
Journal / Book Title: Monthly Notices of the Royal Astronomical Society
Volume: 463
Issue: 4
Copyright Statement: © 2016 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.
Sponsor/Funder: The Royal Society
Commission of the European Communities
Funder's Grant Number: WM110023
FP7-PEOPLE-2012-CIG-321865
Keywords: Science & Technology
Physical Sciences
Astronomy & Astrophysics
Hertzsprung-Russell and colour-magnitude diagrams
Galaxy: formation
globular clusters: general
COLOR-MAGNITUDE DIAGRAMS
HORIZONTAL-BRANCH MORPHOLOGY
SPACE-TELESCOPE PHOTOMETRY
INITIAL HELIUM ABUNDANCE
NA-O ANTICORRELATION
RED GIANT BRANCH
UV LEGACY SURVEY
2ND-GENERATION STARS
MULTIPLE POPULATIONS
OMEGA-CENTAURI
astro-ph.SR
astro-ph.GA
0201 Astronomical And Space Sciences
Publication Status: Published
Appears in Collections:Mathematics
Statistics
Faculty of Natural Sciences



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