Mass determination of astrometric binaries with Hipparcos III. New resultsfor 28 systems

This paper is the third of a series devoted to the determination of stellar masses from Hipparcos data. This is a continuation of Martin et al. (1997) , who introduced the theory and assessed the performance of the method from simulated data, and of a second paper with the first results for 46 system s, (Martin & Mignard 1998). The or bit file maintained by the CHARA group a nd new publications of orbital elements made the processing of 70 additiona l candidate systems possible, including 28 of the 145 systems already teste d in the previous work. Significant results were obtained on 22 systems, wi th relative accuracy better than 25% for the masses of 17 binaries. New est imates are also given for 6 systems previously investigated; thanks to reli able values of the magnitude difference from the Hipparcos catalogue (ESA 1 997). New orbital elements are proposed for HIP 12623 (12 Persei) from spec kle/spectroscopic measurements. Results are discussed for each system, alon gside the mass-luminosity relation based on Hipparcos magnitudes and distan ces.