We present multi–epoch VLBA observations of the compact wind collision region in the Cyg OB2 # 5 system .
These observation confirm the arc-shaped morphology of the emission reported earlier .
The total flux as a function of time is roughly constant when the source is “ on ” , but falls below the detection limit as the wind collision region approaches periastron in its orbit around the contact binary at the center of the system .
In addition , at one of the “ on ” epochs , the flux drops to about a fifth of its average value .
We suggest that this apparent variation could result from the inhomogeneity of the wind that hides part of the flux rather than from an intrinsic variation .
We measured a trigonometrical parallax , for the most compact radio emission of 0.61 \pm 0.22 mas , corresponding to a distance of 1.65 ^ { +0.96 } _ { -0.44 } kpc , in agreement with recent trigonometrical parallaxes measured for objects in the Cygnus X complex .
Using constraints on the total mass of the system and orbital parameters previously reported in the literature , we obtain two independent indirect measurements of the distance to the Cyg OB2 # 5 system , both consistent with 1.3–1.4 kpc .
Finally , we suggest that the companion star responsible for the wind interaction , yet undetected , is of spectral type between B0.5 to O8 .