Variability and pulsations in the Be star 66 Ophiuchi

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 S /N 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 V sini values are obtained using Fourier transforms applied to observed helium lines and a rotational frequency frot = 1.29 cd −1 is determined. Time series analysis and Fourier Doppler Imaging (FDI) of Hei lines (4713, 4921, 5876 and 6678 A) lead for the first time to the detection of multi-periodicity in 66Oph. The two main frequencies found are f = 2.22 cd −1 and f = 4.05 cd −1 . They are attributed to non-radial pulsations and can be associated with mode degree � = 2a nd� = 3, 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.