1998A&A...334L..37I

Stars showing very small amplitudes of radial velocity have been interpreted as systems having planetary companions. For some of them, we present an alternative interpretation in which the star would be a binary system seen face-on, a scheme relying mainly on the fact that the observed amplitude of radial velocity is determined from the blended lines of two stars having close parameters. This model very satisfactorily explains the observational data of 47 UMa, 70 Vir and 16 Cyg B with, however, a low probability. Such systems will certainly occur in the case of large samples. We conclude that in the limited samples available for the moment, almost all the systems with very small amplitudes of radial velocity variations must be considered as planetary systems.