  Cyg OB2 #5 is a contact binary system (O6.5-7+O5.5-6) with associated radio
continuum emission. Two compact ($\leq 0\rlap.{"}3$) radio continuum components
have been reported previously: the primary one is associated with the contact
binary and the secondary one is an arc-like source $\sim 0\rlap.{"}8$ to the NE
of the primary. This arc-like source results from the interaction of the winds
of the contact binary and a B-type star in the region. In this paper we report
the detection of an extended ($\sim 30"$), non-thermal component to the NE of
the compact components. We propose that this extended emission could be an
unresolved background source (i. e. a radio galaxy), extended galactic
emission, or non-thermal emission related with relativistic electrons that are
produced in the shock between the contact binary and the B-type star and that
are carried away to large distances by the wind from the contact binary.

Solar and Stellar Astrophysics