2374 20160701171704.0 ASTROimport-531 Halbwachs, J.-L. 1997 A Statistical Study of the Visual Double Stars in the TYCHO Catalogue The Tycho Catalogue contains reliable (B_T, V_T) photometry for double star components with separations above a limit of about 3 arcsec. These data are used to investigate the distribution of mass ratios of main sequence binaries. For that purpose, two other points are treated first: the correction of Tycho photometry for contamination by neighbour stars, and the derivation of the colour-magnitude diagram in the Tycho photometric system. It appears that the main sequence in the (V_(T abs), B_T - V_T) diagram derived from the Tycho double stars is nearly similar to that obtain from the calibrations selected by Schmidt-Kaler (1982). The distribution of mass ratios, as derived from the mass-luminosity relation, has a rough IMF-like shape with an exponent of about -2. Piquard, S. Virelizier, P. Cuypers, J. Lampens, P. Oblak, E. Hipparcos - Venice '97 402 1997 263-268 http://esoads.eso.org/abs/1997ESASP.402..263H published in NONREF