Schematic view of the geometry of the toy model of the wind interaction zone. The primary star is shown at the origin of the axes, while the secondary is located at x/a = −1. The shock front is computed according to the formalism of Cantó et al. (1996). Only the thick part of the wind intercation zone (corresponding to a maximum radius r_max from the center of the secondary contributes to the X-ray emission). The angle θ_∞ corresponds to the asymptotic shock cone opening angle. The arrows yield the projections of the line of sight at the conjunction phases onto the orbital plane.