EDP Sciences
Free access
Volume 424, Number 3, September IV 2004
Page(s) L39 - L42
Section Letters
DOI http://dx.doi.org/10.1051/0004-6361:200400049

A&A 424, L39-L42 (2004)
DOI: 10.1051/0004-6361:200400049


A Spectroscopic study of the non-thermal radio emitter Cyg OB2 #8A: Discovery of a new binary system

M. De Becker, G. Rauw and J. Manfroid

Institut d'Astrophysique et de Géophysique, Université de Liège, 17, Allée du 6 Août, B5c, 4000 Sart Tilman, Belgium
    e-mail: debecker@astro.ulg.ac.be

(Received 7 May 2004 / Accepted 2 August 2004)

We present the results of a spectroscopic campaign revealing that the non-thermal radio emitter Cyg OB2 #8A is an O6 + O5.5 binary system. We propose the very first orbital solution indicating a period of about 21.9 days. The system appears to be eccentric (0.24  $\pm$ 0.04) and is likely seen under a rather low inclination angle. The mass ratio of the components is close to unity. The impact of the binarity of this star in the framework of our understanding of non-thermal radio emission from early-type stars is briefly discussed.

Key words: binaries: spectroscopic -- stars: early-type -- stars: fundamental parameters -- stars: individual: Cyg OB2 #8A

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© ESO 2004