The Algol-type close binary system SZ Her revised

We present long term ground-based photometric variations of the Algol type binary system SZ Her. Modeling of the system shows that the secondary component is filling Roche lobe. The parameters for the primary and the secondary components have been determined as M-1 = 1.56 +/- 0.05 Me, M-2 = 0.77 +/- 0.03 M-circle dot, R-1 = 1.61 +/- 0.10 R-circle dot, R-2 = 1.55 +/- 0.09 R-circle dot, L-1 = 6.5 +/- 0.5 L-circle dot, L-2 = 1.1 +/- 0.1 L-circle dot while the separation of the components is a = 4.9 +/- 0.3 R-circle dot. Newly obtained parameters yield the distance of the system as 302 +/- 12 pc. We collected all the photometric and CCD times of mid-eclipse available in the literature and combined them with the newly obtained eight times of light minima. Analysis of the mid-eclipse times indicate a period increase of dP/dt = +3.1(2) x 10(-8) days/yr that can be interpreted in terms of the mass transfer rate as dM/dt = +2.62(3) x 10(-9) M-circle dot/yr from the secondary to the primary component. The orbital period of the system oscillates with periods of 118 years and 30 years with corresponding semi-amplitudes of 0.0057 days and 0.0055 days, respectively. These changes were analyzed under the assumption of the existence of third and fourth bodies in the system. (C) 2014 Elsevier B.V. All rights reserved.