Cyclic light and period variations of the UV Leonis system

Abstract

Solutions of the new standard V -light curves for the EA type binary UV Leo are obtained using the PHOEBE code (0.31a version). Absolute parameters of the stellar components were then determined, enabling them to be positioned on the absolute magnitude-color (l.e. MV vs. B − V ) isochrones diagram, based on which the age of the system is estimated to be > 4×10 9 yr. Also times of minima data ("O − C curve") have been analyzed. Apart from an almost sinusoidal variation with a period of 29.63 yr, which modulates the orbital period, and was attributed to a third body orbiting around the system, other cyclic variation in the orbital period and also brightness, with time scales of 24.25 and 22.77 yr were found, respectively. We associate this with a magnetic activity cycle newly reported here for UV Leo.