Hydrodynamic solution of the wind-fed circumstellar matter. The white cross shows the position of the black-hole companion, the black crosses mark the positions of the points L₁ and L₂. The distance scale on the x-axis is labelled in units of the separation between both components of the binary. The right-hand-side colour-scale corresponds to the distribution of the wind density in the equatorial plane. The left-hand-side colour-scale describes the directional dependence of the intensity of the stellar wind projected onto the surface of the supergiant. The red lines represent the streamlines of the stellar wind and the black contour-lines labelled by the corresponding numbers in km s^-1 mark the absolute values of the stream velocity in the orbital plane.