KIC 7582608: a new Kepler roAp star with frequency variability
1 Astrophysics Group, Keele University, Staffordshire ST5 5BG, UK
2 Jeremiah Horrocks Institute, University of Central Lancashire, Preston PR1 2HE, UK
3 Centro de Astrofísca e Faculdade de Ciências, Universidade do Porto, Rua das Estrelas, P-4150-762 Porto, Portugal
4 Department of Astronomy, University of California, Berkeley, CA 94720-3411, USA
a e-mail: firstname.lastname@example.org
Published online: 23 September 2015
We analyse the fifth roAp star reported in the Kepler field, KIC 7582608, discovered with the SuperWASP project. The object shows a high frequency pulsation at 181.7324d−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. Spectral analysis confirms the Ap nature of the target, with characteristic lines of rare earth elements present. 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 β ~ 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 HR diagram where the pulsations are unstable, an area consistent with observations.
© Owned by the authors, published by EDP Sciences, 2015
This is an Open Access article distributed under the terms of the Creative Commons Attribution License 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.