Distributions and relations between stellar parameters for our subsample of 620 stars. Top left: metallicity distribution of the stars of our sample (colored in orange) compared with the same distribution for the ~ 1000 stars (dashed histogram) in the CORALIE volume-limited sample (Udry et al. 2000; Santos et al. 2001). Top right: distribution of the stellar masses obtained from track fitting. The corresponding kernel density estimation is overplotted in orange, using a Gaussian kernel. Bottom left: mass vs. metallicity relation. (bottom right) Metallicity vs. logarithm of surface gravity. The two black lines were drawn by eye and show the biases in the samples due to the B − V cut-off. The red-dashed rectangle delimits the area of the potential unbiased subsample. The three planet hosts presented in this paper are represented by red dots.