Light and period study of the ecipsing binary system TW Andromedae

Abstract

Photoelectric light curve (LC) solutions of the close binary system TW And were obtained using the PHOEBE program (version 0.31a). Absolute parameters of the stellar components were then determined, enabling us to discuss the structure and evolutionary status of TW And. The configuration of the system based on the LCs solutions indicates that the secondary component is slightly detached from its critical Roche surface. In addition, times of minima data ("O -C curve") were analyzed. Apart from an almost parabolic variation of the general trend of the O -C data, indicative of a secular increase in the orbital period with a rate 0.032 s yr −1 , which was attributed to a mass transfer with a rate of Δm2 = −1.10×10−10 M yr −1 . Additionally, a sinusoidal variation with a period of 52.75 ± 1.80 yr, modulating the orbital period, was found, which we attribute to a third body orbiting the system.