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

Amongst the intermediate mass pulsating stars known as $\delta$ Sct stars isa subset of high-amplitude and predominantly radial-mode pulsators known ashigh-amplitude $\delta$ Sct (HADS) stars. From more than 2000 $\delta$ Sctstars observed by the Kepler space mission, only two HADS stars were detected.We investigate the more perplexing of these two HADS stars, KIC5950759. Westudy its variability using ground- and space-based photometry, determine itsatmospheric parameters from spectroscopy and perform asteroseismic modelling toconstrain its mass and evolutionary stage. From spectroscopy, we find thatKIC5950759 is a metal-poor star, which is in agreement with the inferredmetallicity needed to reproduce its pulsation mode frequencies fromnon-adiabatic pulsation models. Furthermore, we combine ground-based WASP andKepler space photometry, and measure a linear change in period of order$\dot{P}/P \simeq 10^{-6}$ yr$^{-1}$ for both the fundamental and firstovertone radial modes across a time base of several years, which is at leasttwo orders of magnitude larger than predicted by evolution models, and is thelargest measured period change in a $\delta$ Sct star to date. Our analysisindicates that KIC5950759 is a metal-poor HADS star near the short-livedcontraction phase and the terminal-age main sequence, with its sub-solarmetallicity making it a candidate SX Phe star. KIC5950759 is a unique objectamongst the thousands of known $\delta$ Sct stars and warrants further study toascertain why its pulsation modes are evolving remarkably faster than predictedby stellar evolution.

KIC5950759: a high-amplitude $\delta$ Sct star with amplitude and frequency modulation near the terminal age main sequence