W UMa-type contact binaries ages and masses

Comparisons of our results with the mean ages from kinematic properties of these binaries and data pertaining to contact binaries in open and globular clusters have increased our confidence on this method. The mean ages of both A- and W-subtype contact binaries are found as 4.4 and 4.6Gyr, respectively. From kinematic studies, these ages are given as 4.5 and 4.4Gyr, respectively.

We also compute orbital properties of A-subtype contact binaries at the time of the first overflow. Initial angular momentum of these binaries is computed by comparing them with the well-known detached binaries. The angular momentum loss rate derived in the present study for the detached phase is in very good agreement with the semi-empirical rates available in the literature.

In addition to the limitations on the initial masses of W UMa-type contact binaries, it is shown that the initial period of these binaries is less than about 4.45d.