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dc.contributor.authorDotter, Aaron
dc.contributor.authorFerguson, Jason W.
dc.contributor.authorConroy, Charlie
dc.contributor.authorMilone, A. P.
dc.contributor.authorMarino, A. F.
dc.contributor.authorYong, David
dc.identifier.citationDotter, Aaron; Ferguson, Jason W.; Conroy, Charlie; Milone, A. P.; Marino, A. F.; Yong, David. 2015. Stellar models of multiple populations in globular clusters - I. The main sequence of NGC 6752. Monthly Notices of the Royal Astronomical Society, vol. 446:no. 2:pp 1641-1656en_US
dc.descriptionClick on the DOI link to access the article (may not be free).en_US
dc.description.abstractWe present stellar atmosphere and evolution models of main-sequence stars in two stellar populations of the Galactic globular cluster NGC 6752. These populations represent the two extremes of light-element abundance variations in the cluster. NGC 6752 is a benchmark cluster in the study of multiple stellar populations because of the rich array of spectroscopic abundances and panchromatic Hubble Space Telescope photometry. The spectroscopic abundances are used to compute stellar atmosphere and evolution models. The synthetic spectra for the two populations show significant differences in the ultraviolet and, for the coolest temperatures, in the near-infrared. The stellar evolution models exhibit insignificant differences in the Hertzsprung-Russell (H-R) diagram except on the lower main sequence. The appearance of multiple sequences in the colour-magnitude diagrams (CMDs) of NGC 6752 is almost exclusively due to spectral effects caused by the abundance variations. The models reproduce the observed splitting and/or broadening of sequences in a range of CMDs. The ultraviolet CMDs are sensitive to variations in carbon, nitrogen, and oxygen but the models are not reliable enough to directly estimate abundance variations from photometry. On the other hand, the widening of the lower main sequence in the near-infrared CMD, driven by oxygen variation via the water molecule, is well described by the models and can be used to estimate the range of oxygen present in a cluster from photometry. We confirm that it is possible to use multiband photometry to estimate helium variations among the different populations, with the caveat that the estimated amount of helium enhancement is model dependent.en_US
dc.description.sponsorshipAustralian Research Council under grant FL110100012. CC received support from NSF grant AST-1313280 and NASA grant NNX13AI46G.en_US
dc.publisherOxford University Pressen_US
dc.relation.ispartofseriesMonthly Notices of the Royal Astronomical Society;v.446:no.2
dc.subjectStars: abundancesen_US
dc.subjectStars: evolutionen_US
dc.subjectGlobular clusters: individual: NGC 6752en_US
dc.titleStellar models of multiple populations in globular clusters - I. The main sequence of NGC 6752en_US
dc.rights.holderCopyright © Oxford University Press 2015

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