Volume 394, Number 1, October IV 2002
|Page(s)||137 - 149|
|Section||Interstellar and circumstellar matter|
|Published online||04 October 2002|
Variability and pulsations in the Be star 66 Ophiuchi*
Observatoire de Paris-Meudon, GEPI, FRE/2459, 92195 Meudon Cedex, France
2 Sterrenkundig Instituut Anton Pannekoek, Universiteit van Amsterdam, Kruislaan 403, Amsterdam, Netherlands
3 Instituto de Astronomia, Geofísica e Ciências Atmosféricas da Universidade de São Paulo, CUASO 05508-900 São Paulo, Brazil
4 Observatoire de la Côte d'Azur, FRESNEL, CNRS UMR 6528, BP 4229, 06304 Nice Cedex, France
5 Astronomska Opservatorija Beograd, MNTRS 1940, Volgina 7, 11050 Beograd, Yugoslavia
6 Institut d'Astrophysique de Paris, 98bis boulevard Arago, 75014 Paris, France
7 Erindale Campus and Department of Astronomy, University of Toronto, Mississauga, ON L5L 1C6, Canada
Corresponding author: M. Floquet, email@example.com
Accepted: 31 July 2002
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.
Key words: stars: emission-line, Be / stars: activity / stars: individual: 66 Oph / stars: oscillations / stars: magnetic field
© ESO, 2002
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