Possible companions of Proxima. The possible companion mass and orbital radius (m₂, r) combinations explaining the observed Δμ_G2 PMa from the GDR2 are shown with the green curve, taking into account the GDR2 time window. The shaded green region corresponds to the 1σ uncertainty domain. The orange vertical line marks the orbital radius whose period corresponds to the GDR2 time window (δt_G2 = 668 d). The permitted (m₂, r) domain for short-period planets from radial velocity searches is shaded in pink. The orbital radii corresponding to periods of P_orb = 1 to 5000 years are indicated with pink vertical marks, with corresponding period values in pink.