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Astron. Astrophys. 320, 497-499 (1997)

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1. Introduction

HD  208217 [FORMULA] CpD [FORMULA] (spectral type A0pSrEuCr) is known to present large photometric variations. On the basis of 15 observations carried out in the uvby system with the 50cm Danish telescope, in September 1981, at the ESO La Silla Observatory, Manfroid & Renson (1983) reported a peak-to-peak amplitude of 0.14 magnitude in the Strömgren [FORMULA] index, largely due to strong variations in the v band. These authors determined the rotation period as [FORMULA]. The uvby data have been reanalyzed by Mathys & Manfroid (1985), who noted a strong anharmonicity of the v lightcurve, the amplitudes of the first two harmonics being approximately equal, respectively 0.0318 and 0.0271 mag.

In 1993 one of us (GM) discovered the presence of magnetically resolved lines in the spectrum of HD 208217 and started observing the variations of the mean magnetic field modulus (for a presentation of the technique, see Mathys (1990)). A rather large Doppler broadening and the presence of blends in the spectra affected the accuracy of the measurements, thus preventing clearcut conclusions to be derived from the magnetic variations. It was obvious, however, that the period initially deduced from the photometric data did not fit well the magnetic observations. A further observational effort was needed.

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© European Southern Observatory (ESO) 1997

Online publication: June 30, 1998
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