Bibcode
Smalley, B.; Niemczura, E.; Murphy, S. J.; Lehmann, H.; Kurtz, D. W.; Holdsworth, D. L.; Cunha, M. S.; Balona, L. A.; Briquet, M.; Bruntt, H.; De Cat, P.; Lampens, P.; Thygesen, A. O.; Uytterhoeven, K.
Bibliographical reference
Monthly Notices of the Royal Astronomical Society, Volume 452, Issue 4, p.3334-3345
Advertised on:
10
2015
Citations
43
Refereed citations
35
Description
We report the identification of 61.45 d-1 (711.2 μHz)
oscillations, with amplitudes of 62.6 μmag, in KIC 4768731 (HD
225914) using Kepler photometry. This relatively bright (V = 9.17)
chemically peculiar star with spectral type A5 Vp SrCr(Eu) has
previously been found to exhibit rotational modulation with a period of
5.21 d. Fourier analysis reveals a simple dipole pulsator with an
amplitude that has remained stable over a 4-yr time span, but with a
frequency that is variable. Analysis of high-resolution spectra yields
stellar parameters of Teff = 8100 ± 200 K, log g = 4.0
± 0.2, [Fe/H] = +0.31 ± 0.24 and v sin i = 14.8 ±
1.6 km s-1. Line profile variations caused by rotation are
also evident. Lines of Sr, Cr, Eu, Mg and Si are strongest when the star
is brightest, while Y and Ba vary in antiphase with the other elements.
The abundances of rare earth elements are only modestly enhanced
compared to other roAp stars of similar Teff and log g.
Radial velocities in the literature suggest a significant change over
the past 30 yr, but the radial velocities presented here show no
significant change over a period of 4 yr.