Binary Star Masses From Hipparcos

The parallaxes from Hipparcos are an important ingredient to derive more accurate masses for known orbital binaries. In order to exploit the parallaxes fully, the orbital elements have to be known to similar precision, and the present work is a first survey of the orbital systems with parallax errors below about 5 per cent. With methods combining the intermediate `Transit Data' (published in the Hipparcos Catalogue) with the existing ground-based data, we have made solutions that improve both the orbital elements and in some cases also the Hipparcos data. In particular, some systems with only a photocentre position or orbit in the Hipparcos Catalogue can now be `resolved' and a magnitude-difference estimated. In all, we have made provisional re-derivations of some 130 sets of orbital elements, giving in the end some 45 mass-sum values with an estimated relative accuracy better than 15 per cent. For some 15 short-period systems, a pure astrometric mass ratio has been determined, but for..