Measurement and study of rotation in close binary stars. III. Statistical analysis of synchronism

This paper presents the statistical relations between synchronism, the fractional radius and the period in close eclipsing binaries. For a given contact type, there is a limiting value of the fractional radius, above which synchronism occurs as a rule. The limiting r is about 0.21 for contact and semi-detached systems, and is 0.18 for detached systems. The difference can, at least partially, be attributed to the mass and angular momentum transfers in the two more compact types.