Companion separation per system with given primary mass in M_⊙. In the range between 1–100 AU, we are sensitive down to 3 M_⊙. There are equally many companion stars in the range 0.1–1 AU as in the range 1–100 AU. The colors indicate different systems, the marker size scales with the square root of the companion mass. The dashes indicate missing information about the mass of the first companion of θ² Ori C and TCC 59.