A&A 477, 907-915 (2008)
Cephei stars in the ASAS-3 data
I. Long-term variations of periods and amplitudesA. Pigulski1 and G. Pojmanski2
1 Instytut Astronomiczny Uniwersytetu Wroclawskiego, Kopernika 11, 51-622 Wroclaw, Poland
2 Obserwatorium Astronomiczne Uniwersytetu Warszawskiego, Al. Ujazdowskie 4, 00-478 Warszawa, Poland
(Received 30 August 2007 / Accepted 7 November 2007)
Aims.We analyse V-filter ASAS-3 photometry of 41 known Cephei-type stars. The ASAS-3 photometry is combined with the archival data, if available, to determine long-term stability of periods and amplitudes of excited modes.
Methods.Frequencies of modes are derived by means of Fourier periodograms with consecutive prewhitening. The results are examined in the context of detection threshold.
Results.We detected amplitude changes in three Cephei stars, BW Cru, V836 Cen, and V348 Nor. Period changes were found in KK Vel and V836 Cen. Our analysis shows that intrinsic period changes are more common among multiperiodic stars, apparently because they are caused by some kind of mode interaction. In addition, we found new modes for seven stars, and for ten others we provide new solutions or remove ambiguities in the detected frequencies. One candidate hybrid Cephei/SPB star, HD 133823, is discovered.
Key words: stars: early-type -- stars: oscillations -- surveys
© ESO 2008