Mass loss and orbital period decrease in detached chromospherically active binaries

Abstract

The secular evolution of the orbital angular momentum (OAM), the systemic mass (M = M-1 + M-2) and the orbital period of 114 chromospherically active binaries (CABs) were investigated after determining the kinematical ages of the subsamples which were set according to OAM bins. OAMs, systemic masses and orbital periods were shown to be decreasing by the kinematical ages. The first-order decreasing rates of OAM, systemic mass and orbital period have been determined as J = 3.48 x 10-(10) yr(-1) per systemic OAM, M = 1.30 x 10-(10) yr(-1) per systemic mass and p = 3.96 x 10(-10) yr(-1) per orbital period, respectively, from the kinematical ages. The ratio of d log J/d log M = 2.68, which were derived from the kinematics of the present sample, implies that there must be a mechanism which amplifies the angular momentum loss (AML) (A) over bar = 2.68 times in comparison to isotropic AML of hypothetical isotropic wind from the components. It has been shown that simple isotropic mass loss from the surface of a component or both components would increase the orbital period.