1996A&A...305L..29M

Stars in binaries cannot be larger than the space available for them. We apply this simple principle to Wolf-Rayet binaries in which the constraints are most severe, i.e. systems with the shortest periods and smallest separations. In particular, analysis of the short-period systems CQ Cep and V444 Cyg leads to observed upper limits for the WR radii that are smaller than the core radii predicted by the so-called "standard model" for WR stars. It is suggested that the standard model tends to systematically underestimate the core temperatures and consequently overestimate the core radii of WR stars in many cases. Correcting for this may place most, if not all, hydrostatic cores of WR stars closer to the He-ZAMS in the H-R diagramme, as expected for such hot, He-rich stars.