ORBITAL CIRCULARIZATION IN DETACHED BINARIES WITH EARLY-TYPE PRIMARIES

Extending our previous study, the present paper reports on the discuss ion of the orbital circularization in 37 detached binaries with early- type primaries. From comparison of the theoretical predictions with th e orbital eccentricities of our binary systems, we find that Zahn's ci rcularization theories are substantially consistent with the observed data for overwhelming majority of our samples. However, we also note t hat three binaries of whom both components are asynchronized rotators possess circular orbits. How to understand the circularism of the thre e systems remains a problem not only to Zahn's theories, but to all ot her present circularization mechanisms.We think that studies on the ci rcularization of pre-main-sequence binary systems could provide some c lues for the problem.