The mass-ratio distribution of spectroscopic binaries along the main sequence

Binarity is now a well-established quality affecting a large fraction of stars, and recent studies have shown that the fraction of binaries is a function of the spectral type of the primary star, with most massive stars being member of a close binary system. By cross-matching the Gaia DR2 catalogue with a catalogue of known spectroscopic orbits, we went one step further and derived the mass ratio distribution of binary systems as a function of the spectral type of the primary star, i.e. of its mass. A clear correlation is found, with B stars showing an excess of low-mass companions and A stars showing an excess of twins.