Rotation, pulsations and outbursts in the Be star upsilon Cyg (HD202904)
Publication date: 02 June 2005
Authors: Neiner, C., et al.
Journal: Astronomy & Astrophysics
Volume: 437
Issue: 1
Page: 257-272
Year: 2005
Copyright: ESO
upsilon Cyg is a Be star which shows variations at all timescales. We monitored its spectrum during several years from 1998 to 2004 and in particular during a spectroscopic multisite campaign in 2000. In this paper we present and analyse the data. We observed several outbursts including an intense one in 2000. Moreover, we found several periods of short-term variations, including two frequencies of non radial pulsations at f~3.0 and 2.6 c/d. The stellar rotation is probably also identified at f~1.5 c/d, which is coherent with the rotation frequency deduced from our determination of stellar parameters. The peak-to-peak amplitude of variations also seems to vary in time, maybe due to a beating effect between close frequencies, but the resolution in time of our data does not allow to separate such close frequencies. Finally, a longer timescale variation is maybe present, with a period around 11 years, which could be associated with a binary companion.
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