Journal Article

<i>Kepler</i> observations of the variability in B-type stars

L. A. Balona, A. Pigulski, P. De Cat, G. Handler, J. Gutiérrez-Soto, C. A. Engelbrecht, F. Frescura, M. Briquet, J. Cuypers, J. Daszyńska-Daszkiewicz, P. Degroote, R. J. Dukes, R. A. Garcia, E. M. Green, U. Heber, S. D. Kawaler, H. Lehmann, B. Leroy, J. Molenda-Żakowicz, C. Neiner, A. Noels, J. Nuspl, R. Østensen, D. Pricopi, I. Roxburgh, S. Salmon, M. A. Smith, J. C. Suárez, M. Suran, R. Szabó, K. Uytterhoeven, Christensen-Dalsgaard, H. Kjeldsen, D. A. Caldwell, F. R. Girouard and D. T. Sanderfer

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 413, issue 4, pages 2403-2420
Published in print June 2011 | ISSN: 0035-8711
Published online May 2011 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2011.18311.x
Kepler observations of the variability in B-type stars

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The analysis of the light curves of 48 B-type stars observed by Kepler is presented. Among these are 15 pulsating stars, all of which show low frequencies, characteristic of slowly pulsating B (SPB) stars. Seven of these stars also show a few weak, isolated high frequencies and they could be considered as SPB/β Cephei (β Cep) hybrids. In all cases, the frequency spectra are quite different from what is seen from ground-based observations. We suggest that this is because most of the low frequencies are modes of high degree which are predicted to be unstable in models of mid-B stars. We find that there are non-pulsating stars within the β Cep and SPB instability strips. Apart from the pulsating stars, we can identify stars with frequency groupings similar to what is seen in Be stars but which are not Be stars. The origin of the groupings is not clear, but may be related to rotation. We find periodic variations in other stars which we attribute to proximity effects in binary systems or possibly rotational modulation. We find no evidence for pulsating stars between the cool edge of the SPB and the hot edge of the δ Sct instability strips. None of the stars shows the broad features which can be attributed to stochastically excited modes as recently proposed. Among our sample of B stars are two chemically peculiar stars, one of which is a HgMn star showing rotational modulation in the light curve.

Keywords: stars: early-type; stars: oscillations

Journal Article.  12919 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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