Open questions in binary star statistics and the contribution of GAIA to solve them

摘要

The statistical properties of binary stars are still poorly known, since it is difficult to prepare samples of double stars with homogeneous and corrigible selection effects. However, it seems that the distributions of mass ratios, periods and eccentricities are rather complex and that binaries are generated by at least two different formation processes. The GAIA radial velocity survey and the GAIA astrometry will dramatically change the deal, by providing enormous samples of spec-troscopic binaries and of long-period binaries covering almost the whole range of mass ratios. For this purpose, the best resolution of the spectro-graph should be R= 20000 rather than R= 5000.