  This paper presents calculations for forbidden emission line profile shapes
arising from colliding wind binaries. The main application is for systems
involving a Wolf-Rayet (WR) star and an OB star companion. The WR wind is
assumed to dominate the forbidden line emission. The colliding wind interaction
is treated as an archimedean spiral with an inner boundary. Under the
assumptions of the model, the major findings are as follows. (a) The
redistribution of the WR wind as a result of the wind collision is not flux
conservative but typically produces an excess of line emission; however, this
excess is modest at around the 10% level. (b) Deviations from a flat-top
profile shape for a spherical wind are greatest for viewing inclinations that
are more nearly face-on to the orbital plane. At intermediate viewing
inclinations, profiles display only mild deviations from a flat-top shape. (c)
The profile shape can be used to constrain the colliding wind bow shock opening
angle. (d) Structure in the line profile tends to be suppressed in binaries of
shorter periods. (e) Obtaining data for multiple forbidden lines is important
since different lines probe different characteristic radial scales. Our models
are discussed in relation to ISO data for WR 147 and gamma Vel (WR11). The
lines for WR 147 are probably not accurate enough to draw firm conclusions. For
gamma Vel, individual line morphologies are broadly reproducible but not
simultaneously so for the claimed wind and orbital parameters. Overall, the
effort demonstrates how lines that are sensitive to the large-scale wind can
help to deduce binary system properties and provide new tests of numerical
simulations.
