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KIC 5950759: a high-amplitude δ Sct star with amplitude and frequency modulation near the terminal age main sequence

M. Bowman, D.; Hermans, J.; Daszyńska-Daszkiewicz, J.; L. Holdsworth, D.; Tkachenko, A.; J. Murphy, S.; Smalley, B.; W. Kurtz, D.

KIC 5950759: a high-amplitude δ Sct star with amplitude and frequency modulation near the terminal age main sequence Thumbnail


D. M. Bowman

J. Hermans

J. Daszyńska-Daszkiewicz

D. L. Holdsworth

A. Tkachenko

S. J. Murphy

D. W. Kurtz


Amongst the intermediate mass pulsating stars known as d Sct stars is a subset of high-amplitude and predominantly radial-mode pulsators known as high-amplitude d Sct (HADS) stars. From more than 2000 d Sct stars observed by the Kepler space mission, only two HADS stars were detected. We investigate the more perplexing of these two HADS stars, KIC 5950759. We study its variability using ground- and space-based photometry, determine its atmospheric parameters from spectroscopy and perform asteroseismic modelling to constrain its mass and evolutionary stage. From spectroscopy, we find that KIC 5950759 is a metal-poor star, which is in agreement with the inferred metallicity needed to reproduce its pulsation mode frequencies from non-adiabatic pulsation models. Furthermore, we combine ground-based WASP and Kepler space photometry, and measure a linear change in period of order \\$\\dot\\{P\\}/P \\simeq 10^\\{-6\\}\\$ yr-1 for both the fundamental and first overtone radial modes across a time base of several years, which is at least two orders of magnitude larger than predicted by evolution models, and is the largest measured period change in a d Sct star to date. Our analysis indicates that KIC 5950759 is a metal-poor HADS star near the short-lived contraction phase and the terminal-age main sequence, with its sub-solar metallicity making it a candidate SX Phe star. KIC 5950759 is a unique object amongst the thousands of known d Sct stars and warrants further study to ascertain why its pulsation modes are evolving remarkably faster than predicted by stellar evolution.

Journal Article Type Article
Acceptance Date Apr 16, 2021
Online Publication Date Apr 21, 2021
Publication Date 2021-07
Publicly Available Date May 30, 2023
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Publisher Oxford University Press
Peer Reviewed Peer Reviewed
Volume 504
Issue 3
Pages 4039-4053
Keywords asteroseismology, oscillations, variables: d Scuti, HADS, SX PhE, Individual, KIC 5950759
Publisher URL


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