Detection limits for the 15 stars studied in this work. The plots show planetary mass against orbital period. The thick black line shows the 99% detection limits, estimated by injecting trial circular orbits. The dashed blue lines represent circular planetary signals with RV semi-amplitudes of 1, 3, and 5 ms^-1 (from bottom to top in each panel). The regions delimited by the red dotted lines correspond to periods lower than 50 d, and masses in the ranges M = 10−30 M_⊕ and M = 30−100 M_⊕.