Smalley, B., Niemczura, E., Murphy, S. J., Lehmann, H., Kurtz, Donald Wayne, Holdsworth, D. L., Cunha, M. S., Balona, L. A., Briquet, M., Bruntt, H., De Cat, P., Lampens, P., Thygesen, A. O. and Uytterhoeven, K. (2015) KIC 4768731: a bright long-period roAp star in theKeplerfield. Monthly Notices of the Royal Astronomical Society, 452 (4). pp. 3334-3345. ISSN 0035-8711
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Official URL: http://dx.doi.org/10.1093/mnras/stv1515
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.
|Uncontrolled Keywords (separate with ;):||asteroseismology – techniques; photometric – stars; abundances – stars; chemi- cally peculiar – stars; individual; KIC 4768731 – stars; oscillations.|
|Subjects:||Physical sciences > Astronomy|
|Schools:||Faculty of Science and Technology > School of Physical Sciences and Computing > Jeremiah Horrocks Institute|
|Deposited By:||Nuala Jones|
|Deposited On:||09 May 2016 10:44|
|Last Modified:||07 Mar 2017 03:21|
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