Left panel: 3D rendering showing the five sources (gray spheres, volumes proportional to strength of the source), four null points (yellow spheres), spine stream lines (black lines), and four separatrix surfaces (semi-transparent blue, red, green, cyan)emanating from the nulls, together with some of their constituting fan stream lines. Only parts of objects within a sphere of radius 5 around the origin are shown. Right panel: perspective projection of a spherical surface of radius R = 10, color-coded by the source from which stream lines passing through a given point on the sphere originate, thus indicating the extent and geometrical shape of the solid angle that is filled by the wind from the corresponding stellar source. The colors of sources 1 (cyan), 2 (blue), 3 (red), and 4 (green) correspond to those of the null (as used in the left image) to which the respective source is connected by a streamline. The patch for the central source (filling the small lanes between the other four patches) is omitted.