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

Binary stars are thought to be a controlling factor in globular clusterevolution, since they can heat the environmental stars by converting theirbinding energy to kinetic energy during dynamical interactions. Through suchinteraction, the binaries determine the time until core collapse. To testpredictions of this model, we have determined binary fractions for 35 clusters.Here we present our methodology with a representative globular cluster NGC4590. We use HST archival ACS data in the F606W and F814W bands and applyPSF-fitting photometry to obtain high quality color-magnitude diagrams. Weformulate the star superposition effect as a Poisson probability distributionfunction, with parameters optimized through Monte-Carlo simulations. Amodel-independent binary fraction of (6.2 +- 0.3)% is obtained by countingstars that extend to the red side of the residual color distribution afteraccounting for the photometric errors and the star superposition effect. Amodel-dependent binary fraction is obtained by constructing models with a knownbinary fraction and an assumed binary mass-ratio distribution function. Thisleads to a binary fraction range of 6.8% to 10.8%, depending on the assumedshape to the binary mass ratio distribution, with the best fit occurring for abinary distribution that favors low mass ratios (and higher binary fractions).We also represent the method for radial analysis of the binary fraction in therepresentative case of NGC 6981, which shows a decreasing trend for the binaryfraction towards the outside, consistent with theoretical predictions for thedynamical effect on the binary fraction.

Binary Frequencies in a Sample of Globular Clusters. I. Methodology and Initial Results