KIC 7582608: a new Kepler roAp star with frequency variability

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

Abstract

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 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 HR diagram where the pulsations are unstable, an area consistent with observations.

• Presentation Conference Type: Poster
• Conference Name: The Space Photometry Revolution – CoRoT Symposium 3, Kepler KASC-7 Joint Meeting
• Conference Location: Toulouse, France
• Start Date: Jul 6, 2014
• End Date: Jul 11, 2014
• Publicly Available Date: May 26, 2023
• Publisher: Società Italiana di Fisica
• Series Title: EPJ Web of Conferences
• DOI: https://doi.org/10.1051/epjconf/201510106033
• Publisher URL: http://dx.doi.org/10.1051/epjconf/201510106033
• Additional Information: POSTER SESSION