Halbwachs, J.-L. ; Piquard, S. ; Virelizier, P. ; Cuypers, J. ; Lampens, P. ; Oblak, E.

published in Hipparcos - Venice '97, 402, pp. 263-268 (1997)

Abstract: 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.

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