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Astron. Astrophys. 326, 620-628

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Multiwavelength studies of Cephei stars: Ceti

H. Cugier and D. Nowak

Astronomical Institute of the Wroclaw University, ul. Kopernika 11, PL-51622 Wroclaw, Poland

Received 22 April 1996 / Accepted 21 March 1997


We discuss diagnostic aspects that follow from identification of the driving mechanism for the pulsation of FORMULA Cephei stars by an analysis of the well-observed star FORMULA Ceti. Ground-based photometric and ultraviolet IUE spectro-photometric observations were used. We find that the stellar model which fits the observed frequency of oscillation and nonadiabatic observables (amplitude ratios and phase differences of the multicolour photometric measurements) describes also very well the energy flux distribution and spectral line profiles. Stellar models calculated for OPAL opacities with Z = 0.02 fit the observations best.

We find that FORMULA Ceti is a star pulsating in the first overtone (p2) of the radial (l = 0) mode. The luminosity of this star is in the range of 4.04 FORMULA log FORMULA 4.16 and mass FORMULA . We also discuss how these parameters can be improved using nonadiabatic observables.

Key words: FORMULA Cephei stars - stars: oscillations - stars: early-type - stars: atmosphere - stars: variable: other

Send offprint requests to: H. Cugier

© European Southern Observatory (ESO) 1997

Online publication: September 18, 1997
Last change: October 15, 1997