Non-thermal radio emission from O-type stars III. Is Cyg OB2 No. 9 a wind-colliding binary?

S. Van Loo; R. Blomme; S. M. Dougherty; M. C. Runacres

doi:10.1051/0004-6361:200809367

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arXiv · 0803.2607

Non-thermal radio emission from O-type stars III. Is Cyg OB2 No. 9 a wind-colliding binary?

S. Van Loo·R. Blomme·S. M. Dougherty·M. C. Runacres

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Abstract

The star Cyg OB2 No. 9 is a well-known non-thermal radio emitter. Recent theoretical work suggests that all such O-stars should be in a binary or a multiple system. However, there is no spectroscopic evidence of a binary component. Re-analysis of radio observations from the VLA of this system over 25 years has revealed that the non-thermal emission varies with a period of 2.35+-0.02 yr. This is interpreted as a strong suggestion of a binary system, with the non-thermal emission arising in a wind-collision region. We derived some preliminary orbital parameters for this putative binary and revised the mass-loss rate of the primary star downward from previous estimates.

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S. Van Loo, R. Blomme, S. M. Dougherty, M. C. Runacres. 2008-03-18. Non-thermal radio emission from O-type stars III. Is Cyg OB2 No. 9 a wind-colliding binary?. https://doi.org/10.1051/0004-6361:200809367

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