[en] 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.
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Balona, L. A.; South African Astronomical Observatory, PO Box 9, Observatory 7935, Cape Town, South Africa
Pigulski, A.; Instytut Astronomiczny, Uniwersytet Wrocławski, Kopernika 11, 51-622 Wrocław, Poland
Cat, P De; Koninklijke Sterrenwacht van België, Ringlaan 3, B-1180 Brussels, Belgium
Handler, G.; Institut für Astronomie, Universität Wien, Vienna, Austria
Gutiérrez-Soto, J.; Instituto de Astrofísica de Andalucía, CSIC, PO Box 3004, 18080 Granada, Spain ; LESIA, Observatoire de Paris, CNRS, UPMC, Université Paris-Diderot, 92195 Meudon, France
Engelbrecht, C. A.; Department of Physics, University of Johannesburg, South Africa
Frescura, F.; School of Physics, University of the Witwatersrand, Johannesburg, South Africa
Briquet, Maryline ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Astrophysique stellaire théorique et astérosismologie
Molenda-Żaaowicz, J.; Instytut Astronomiczny, Uniwersytet Wrocławski, Kopernika 11, 51-622 Wrocław, Poland
Neiner, C.; LESIA, Observatoire de Paris, CNRS, UPMC, Université Paris-Diderot, 92195 Meudon, France
Noels-Grötsch, Arlette ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Département d'astrophys., géophysique et océanographie (AGO)
Nuspl, J.; Queen Mary University of London, Mile End Road, London E1 4NS
Østensen, R.; Instituut voor Sterrenkunde, Katholieke Universiteit Leuven, Celestijnenlaan 200D, B-3001 Leuven, Belgium
Pricopi, D.; Astronomical Institute of the Romanian Academy, Bucharest, Romania
Roxburgh, I.; Queen Mary University of London, Mile End Road, London E1 4NS
Salmon, Sébastien ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Astrophysique stellaire théorique et astérosismologie
Smith, M. A.; Space Telescope Science Institute, Baltimore, MD 21218, USA
Suárez, J. C.; Instituto de Astrofísica de Andalucía, CSIC, PO Box 3004, 18080 Granada, Spain
Suran, M.; Astronomical Institute of the Romanian Academy, Bucharest, Romania
Szabó, R.; Konkoly Observatory of the Hungarian Academy of Sciences, Budapest, Hungary
Uytterhoeven, K.; Laboratoire AIM, CEA/DSM-CNRS-Université Paris Diderot ; IRFU/SAp, Centre de Saclay, 91191 Gif-sur-Yvette, France
Christensen-Dalsgaard, J.; Department of Physics and Astronomy, Building 1520, Aarhus University, 8000 Aarhus C, Denmark
Kjeldsen, H.; Department of Physics and Astronomy, Building 1520, Aarhus University, 8000 Aarhus C, Denmark
Caldwell, D. A.; SETI Institute/NASA Ames Research Center, Moffett Field, CA 94035, USA
Girouard, F. R.; Orbital Sciences Corporation/NASA Ames Research Center, Moffett Field, CA 94035, USA
Sanderfer, D. T.; NASA Ames Research Center, Moffett Field, CA 94035, USA
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