Constraints on the orbital period and the companion mass M₂ set by the Δμ criterion (Eq. (7); above the blue line) and by the Roche lobe criterion (Eq. (10); below the red line) adopting a stellar radius of 420 R_⊙ and a primary mass of 1.5 M_⊙. The latter condition imposes the companion to be less massive than 1.5 M_⊙ (below the dashed horizontal line). The ability to detect a Δμ binary moreover imposes 1500 < P(days) < 30 000 (between both vertical dashed lines). The admissible region is enclosed within these boundaries (green area).