2001A&A...376..586F

High angular resolution observations have shown that some stars classified as λ Boo are binaries with low values of angular separation and magnitude difference of the components; therefore the observed spectrum of these objects is a combination of those two components. These composite spectra have been used to define spectroscopic criteria able to detect other binaries among stars classified as λ Boo. The application of this method to HD 111786 is presented: the contribution of 5 components to the observed spectrum is demonstrated by the shape of the O I 7774Å feature. This result makes unreliable any attempt to perform an abundance analysis of this object which therefore must be definitely rejected from the class of the peculiar λ Boo stars. This approach allowed us also to recognize that the SB2 star HD 153808 is in reality a triple system.