A first detailed study of the colliding wind WR+O binary WR 30a |
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Authors: | E. Gosset &dagger ,P. Royer,G. Rauw&Dagger § ,J. Manfroid¶ ,J.-M. Vreux |
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Affiliation: | Institut d'Astrophysique et de Géophysique, Universitéde Liège, Avenue de Cointe, 5, B-4000 Liège, Belgium |
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Abstract: | We present a detailed, extensive investigation of the photometric and spectroscopic behaviour of WR 30a. This star is definitely a binary system with a period around 4.6 d. We propose the value . The identification of the components as WO4+O5((f)) indicates a massive evolved binary system; the O5 component is a main-sequence or, more likely, a giant star. The radial velocities of the O star yield a circular orbit with an amplitude and a mass function of 0.013 . The spectrum of WR 30a exhibits strong profile variations of the broad emission lines that are phase-locked with the orbital period. We report the detection of the orbital motion of the WO component with , but this should be confirmed by further observations. If correct, it implies a mass ratio . The star exhibits sinusoidal light variations of amplitude 0.024 mag peak-to-peak with the minimum of light occurring slightly after the conjunction with the O star in front. On the basis of the phase-locked profile variations of the C iv λ 4658 blend in the spectrum of the WO, we conclude that a wind–wind collision phenomenon is present in the system. We discuss some possibilities for the geometry of the interaction region. |
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Keywords: | binaries: spectroscopic stars: individual: WR 30a stars: mass-loss stars: Wolf–Rayet |
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