The SARG Exo - Planets Search: The sample

With the two aims described in the aims section, we selected from Hipparcos Multiple Stars Catalog a sample of binary systems with separation larger than 2 arcsec (to avoid contamination of the spectra), magnitude difference less than 1.0 mag (a small magnitude difference is useful in comparison of chemical composition of the components, avoiding systematic effects due to different temperatures and gravities), colors in the range 0.45 < (B-V) < 1.1, parallaxes larger than 10.0 mas (with errors smaller than 5 mas) and declination d > -20. Typical projected separations are in the range 100-1000 AU. Dynamical stability for a planet up to 20-30 AU from the star is possible in most cases, according to the simulations of Holman & Wiegert (1999, AJ 117, 621). Among the planets already discovered, one orbits around a star in a binary system with projected separation 150~AU (HD 195019, Fischer et al. 1999, PASP 111, 50). 

In the figure the distribution of the projected separation of the pairs in the sample is shown.