The common convective envelope model for W Ursae Majoris systems and the analysis of their light curves

Abstract

The common convective envelope model for W UMa systems is used to analyse the light curves of the sixteen systems with spectroscopic mass ratios. From the derived photometric elements, an indication is found that Binnendijk's W-type systems have only shollow common envelopes, which is therefore suggested to be the cause of the difference between A- and W-type systems. It is also suggested that the structure of many contact binaries permits only a shallow common envelope and that further study of such envelopes will yield the modification in the model required if a closer fit to the W-type light curves is to be obtained.