Illustration of the twin method applied to the Pleiades cluster. The coordinates of the stars used in this work are shown in the upper panel. The blue circle represents the location of the Pleiades cluster, the black crosses are the reference Hipparcos field stars, and the black squares are the twins of the Pleiades stars found in the field. The bottom left panel shows the colour−magnitude diagram of the Pleiades, including the stars of the Seven Sister DANCe catalogue (Bouy et al. 2015) for reference with crosses. Circles correspond to the stars for which we took HARPS spectra, and the red triangles correspond to stars with twins in the field. A selection of Pleiades members with different spectra are shown around the Mg I triplet in red in the bottom right plot, together with a spectrum of a twin in the field as a dotted black line. The name of the Pleiades star and its corresponding twin are indicated, as well as its distance. Fast rotators are Pels 17, Pels 35, and Pels 174, which is seen in the greater broadening of their lines.