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 Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

The RR Lyrae instability strip (IS) in NGC 1851 is investigated, and a modelis presented which reproduces the pulsational properties of the RR Lyraepopulation. In our model, a stellar component within the IS that displays minorhelium variations (Y~0.248-0.270) is able to reproduce the observed periods andamplitudes of the RR Lyrae variables, as well as the frequency of fundamentaland first-overtone RR Lyrae variables. The RR Lyrae variables therefore maybelong to an He-enriched second generation of stars. The RR Lyrae variableswith a slightly enhanced helium (Y~0.270-0.280) have longer periods at a givenamplitude, as is seen with Oosterhoff II (OoII) RR Lyrae variables, whereas theRR Lyrae variables with Y~0.248-0.270 have shorter periods, exhibitingproperties of Oosterhoff I (OoI) variables.

Theoretical Modeling of the RR Lyrae Variables in NGC 1851