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 report the first estimate of the He abundance of the population of RRLyrae stars in the Galactic bulge. This is done by comparing the recentobservational data with the latest models. We use the large samples of ab typeRR Lyrae stars found by OGLE IV in the inner bulge and by the VVV survey in theouter bulge. We present the result from the new models computed by Marconi etal. (2017), showing that the minimum Period for fundamental RR Lyrae pulsatorsdepends on the He content. By comparing these models with the observations in aPeriod versus effective temperature plane, we find that the bulk of the bulgeab type RR Lyrae are consistent with primordial He abundance Y=0.245, rulingout a significant He-enriched population. This work demonstrates that the Hecontent of the bulge RR Lyrae is different from that of the bulk of the bulgepopulation as traced by the red clump giants, that appear to be significantlymore He-rich.

Gauging the Helium Abundance of the Galactic Bulge RR Lyrae Stars