Variability and pulsations in the Be star 66 Ophiuchi

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Abstract
66 Oph is a Be star seen under a moderate inclination angle that shows strong variability from UV to IR wavelengths. A concise review of long-term variability history is given. High resolution, high spectroscopic observations obtained in 1997, 1998 and 2001 and spectropolarimetric observations obtained in 2000 are presented. These observations occurred during a long-term decrease of Hα intensity. Fundamental parameters of the star have been revisited from Barbier-Chalonge-Divan (BCD) calibrations. New values are obtained using Fourier transforms applied to observed helium lines and a rotational frequency c d-1 is determined. Time series analysis and Fourier Doppler Imaging (FDI) of lines (4713, 4921, 5876 and 6678 Å) lead for the first time to the detection of multi-periodicity in 66 Oph. The two main frequencies found are c d-1 and c d-1 . They are attributed to non-radial pulsations and can be associated with mode degree and , respectively. Inspection of Stokes V profiles suggests the presence of a weak Zeeman signature but further observations are needed to confirm the detection of a magnetic field in 66 Oph.

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