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KIC 7582608: a new Kepler roAp star with frequency variability

Holdsworth, Daniel L.; Smalley, B.; Kurtz, D. W.; Southworth, J.; Cunha, M. S.; Clubb, K. I.

KIC 7582608: a new Kepler roAp star with frequency variability Thumbnail


Daniel L. Holdsworth

D. W. Kurtz

M. S. Cunha

K. I. Clubb


We analyse the fifth rapidly oscillating Ap (roAp) star reported in the Kepler field, KIC 7582608, discovered with the SuperWASP (Wide Angle Search for Planets) project. The object shows a high-frequency pulsation at 181.7324 d-1 (P = 7.9 min) with an amplitude of 1.45 mmag, and low-frequency rotational modulation corresponding to a period of 20.4339 d with an amplitude of 7.64 mmag. Spectral analysis confirms the Ap nature of the target, with characteristic lines of Eu II, Nd III and Pr III present. The spectra are not greatly affected by broadening, which is consistent with the long rotational period found from photometry. From our spectral observations we derive a lower limit on the mean magnetic field modulus of <B> = 3.05 ± 0.23 kG. Long cadence Kepler observations show a frequency quintuplet split by the rotational period of the star, typical for an oblique pulsator. We suggest the star is a quadrupole pulsator with a geometry such that i ~ 66° and ß ~ 33°. We detect frequency variations of the pulsation in both the WASP and Kepler data sets on many time-scales. Linear, non-adiabatic stability modelling allows us to constrain a region on the Hertzsprung–Russell diagram where the pulsations are unstable, an area consistent with observations.

Journal Article Type Article
Acceptance Date Jul 6, 2015
Online Publication Date Jul 28, 2014
Publication Date Sep 21, 2014
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Publisher Oxford University Press
Peer Reviewed Peer Reviewed
Volume 443
Issue 3
Pages 2049 - 2062
Keywords asteroseismology; photometric; chemically peculiar; KIC 7582608; oscillations
Publisher URL


B Smalley - KIC 4768731 - a bright long period roAp star in the Kepler Field.pdf (985 Kb)

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