EDP Sciences
Free Access
Volume 432, Number 3, March IV 2005
Page(s) 955 - 967
Section Stellar structure and evolution
DOI https://doi.org/10.1051/0004-6361:20041444

A&A 432, 955-967 (2005)
DOI: 10.1051/0004-6361:20041444

Disentangling component spectra of , a spectroscopic binary with a pulsating primary

II. Interpretation of the line-profile variability
K. Uytterhoeven1, M. Briquet1, C. Aerts1, 2, J. H. Telting3, P. Harmanec4, 5, K. Lefever1 and J. Cuypers6

1  Institute of Astronomy, Katholieke Universiteit Leuven, Celestijnenlaan 200 B, 3001 Leuven, Belgium
    e-mail: Katrien.Uytterhoeven@ster.kuleuven.ac.be
2  Department of Astrophysics, University of Nijmegen, PO Box 9010, 6500 GL Nijmegen, The Netherlands
3  Nordic Optical Telescope, Apartado de Correos 474, 38700 Santa Cruz de La Palma, Spain
4  Astronomical Institute of the Charles University, V Holesovickách 2, 180 00 Praha 8, Czech Republic
5  Astronomical Institute, Academy of Sciences, 251 65 Ondrejov, Czech Republic
6  Royal Observatory of Belgium, Ringlaan 3, 1180 Brussel, Belgium

(Received 10 June 2004 / Accepted 31 October 2004)

We analyse the complex short-term line-profile variability of the spectroscopic binary $\beta\,$Cep star after orbit subtraction, before and after spectral disentangling. We refine the known oscillation frequency of the star: f1=4.99922 c$\,$d-1 and detect 2f1. Variability is also found at frequencies near $f_2\simeq 4.85$ c$\,$d-1 and $f_3\simeq 5.69$ c$\,$d-1 or their aliases. These frequencies are not significant if we consider the spectra alone, but they survive our selection after the consideration that they were derived previously from independent ground-based and space photometry by different teams. Moreover, we find dominant variability in the equivalent width with a frequency in the interval [0.22,0.30] c d-1 which we interpret as the rotational frequency $f_{\rm rot}$ of the star. The complex window function does not allow us to determine definite values for $f_2, f_3, f_{\rm rot}$. The variability with f1 is interpreted as a prograde non-radial oscillation mode with spherical wavenumbers $(\ell,m)=(2,-1)$ or (1,-1). The additional frequencies are explained in terms of rotational modulation superposed to the main oscillation. We also point out that we cannot disprove the variability in to originate from co-rotating structures. KOREL disentangling preserves the large-amplitude line-profile variability but its performance for complex low-amplitude variability remains to be studied in detail.

Key words: binaries: spectroscopic -- stars: oscillations -- line: profiles -- stars: individual:

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© ESO 2005