Radial velocities of the contact binary system RW Doradus

Radial velocities are reported for both components of the short-period contact binary RW Dor. Although the data set is limited to nine observations of one half of the orbital cycle, and two observations of the other half, the mass ratio and the minimum masses are determined to precisions of 5 per cent. These results are then combined with those from wide-ranging analyses of extensive photometric observations by Kaluzny & Caillault (1989, Acta Astr., 39) and Marton et al. (1989, MNRAS, 240) to establish the masses and other astrophysical parameters of the system for the first time. The system is confirmed to be a W-type contact binary composed of two K-type stars. It is therefore one of the lowest mass W-type systems known and has properties typical of such contact binaries