EDP Sciences
Free access
Volume 477, Number 3, January III 2008
Page(s) 907 - 915
Section Stellar structure and evolution
DOI http://dx.doi.org/10.1051/0004-6361:20078580

A&A 477, 907-915 (2008)
DOI: 10.1051/0004-6361:20078580

$\beta$ Cephei stars in the ASAS-3 data

I. Long-term variations of periods and amplitudes
A. Pigulski1 and G. Pojmanski2

1  Instytut Astronomiczny Uniwersytetu Wroclawskiego, Kopernika 11, 51-622 Wroclaw, Poland
    e-mail: pigulski@astro.uni.wroc.pl
2  Obserwatorium Astronomiczne Uniwersytetu Warszawskiego, Al. Ujazdowskie 4, 00-478 Warszawa, Poland
    e-mail: gp@astrouw.edu.pl

(Received 30 August 2007 / Accepted 7 November 2007)

Aims.We analyse V-filter ASAS-3 photometry of 41 known $\beta$ 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 $\beta$ 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 $\beta$ Cephei/SPB star, HD 133823, is discovered.

Key words: stars: early-type -- stars: oscillations -- surveys

© ESO 2008