Non-thermal radio emission from O-type stars III. Is Cyg OB2 No. 9 a wind-colliding binary?
arXiv:0803.2607 · doi:10.1051/0004-6361:200809367
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.
arXiv comment13 pages, 5 figures, includes online data, accepted by A&A
References in corpus (10)
- The Discordance of Mass-Loss Estimates for Galactic O-Type Stars
- Low mass loss rates in O-type stars: Spectral signatures of dense clumps in the wind of two Galactic O4 stars
- High resolution radio observations of the colliding-wind binary WR140
- Radio, X-ray, and gamma-ray Emission Models of the Colliding Winds Binary WR 140
- A Radial Velocity Survey of the Cygnus OB2 Association
- WR20a: a massive cornerstone binary system comprising two extreme early-type stars
- Radio emission models of Colliding-Wind Binary Systems - Inclusion of IC cooling
- A pseudo-planar, periodic-box formalism for modelling the outer evolution of structure in spherically expanding stellar winds
- Non-thermal radio emission from O-type stars. II. HD 167971
- Non-thermal radio emission from O-type stars. I. HD 168112
Cited by in corpus (14)
- The Galactic O-Star Spectroscopic Survey. I. Classification System and Bright Northern Stars in the Blue-Violet at R~2500
- Catalogue of particle-accelerating colliding-wind binaries
- Early Results from the Galactic O-Star Spectroscopic Survey: C III Emission Lines in Of Spectra
- 3D models of radiatively driven colliding winds in massive O+O star binaries - III. Thermal X-ray emission
- 3D models of radiatively driven colliding winds in massive O+O star binaries - II. Thermal radio to sub-mm emission
- Non-thermal radio emission from O-type stars. IV. Cyg OB2 No. 8A
- Modelling the radio emission from Cyg OB2 #5: a quadruple system?
- The 2.35 year itch of Cyg OB2 #9 - I. Optical and X-ray monitoring
- A binary signature in the non-thermal radio-emitter Cyg OB2 #9
- The 2.35 year itch of Cyg OB2 #9. II. Radio monitoring
- A test for the theory of colliding winds: the periastron passage of 9 Sagittarii I. X-ray and optical spectroscopy
- Radio variability in the Phoenix Deep Survey at 1.4GHz
- The 2.35 year itch of Cygnus OB2#9 III. X-ray and radio emission analysis based on three dimensional hydrodynamical modelling
- Non-thermal radio emission from colliding-wind binaries: modelling Cyg OB2 No. 8A and No. 9