English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

We present stellar atmosphere and evolution models of main sequence stars intwo stellar populations of the Galactic globular cluster NGC 6752. Thesepopulations represent the two extremes of light-element abundance variations inthe cluster. NGC 6752 is a benchmark cluster in the study of multiple stellarpopulations because of the rich array of spectroscopic abundances andpanchromatic Hubble Space Telescope photometry. The spectroscopic abundancesare used to compute stellar atmosphere and evolution models. The syntheticspectra for the two populations show significant differences in the ultravioletand, for the coolest temperatures, in the near-infrared. The stellar evolutionmodels exhibit insignificant differences in the H-R diagram except on the lowermain sequence. The appearance of multiple sequences in the colour-magnitudediagrams (CMDs) of NGC 6752 is almost exclusively due to spectral effectscaused by the abundance variations. The models reproduce the observed splittingand/or broadening of sequences in a range of CMDs. The ultraviolet CMDs aresensitive to variations in carbon, nitrogen, and oxygen but the models are notreliable enough to directly estimate abundance variations from photometry. Onthe other hand, the widening of the lower main sequence in the near-infraredCMD, driven by oxygen-variation via the water molecule, is well-described bythe models and can be used to estimate the range of oxygen present in a clusterfrom photometry. We confirm that it is possible to use multiband photometry toestimate helium variations among the different populations, with the caveatthat the estimated amount of helium-enhancement is model-dependent.

Stellar Models of Multiple Populations in Globular Clusters. I. The Main Sequence of NGC 6752