Period and light-curve study of the contact eclipsing binary V523 Cas

• V523 Cas has a pulsating component.
• The new ephemeris and the mass transfer rate of the system is calculated.
• Minimum masses of the third body and the fourth body of the system is estimated.

CCD photometry of the eclipsing W Uma binary system V523 Cas in U, B, V and RC   filters was carried out during eight nights in 2012. The physical and geometrical parameters of this system are obtained. A possible pulsation period of one of the components is obtained by analyzing the residuals of the ephemeris light curve. Our observations contain 16 times of minimum light. We combined these with all available published times of minimum. By fitting a quadratic curve to the O-C values, a new ephemeris of the system is calculated. By attributing the period change to mass transfer, we find a mass transfer rate of 4×10−124×10−12M⊙yr. Also, Period (80.58 yr) and the minimum mass (0.3 M⊙) of a possible third body is estimated. In addition, the possible existence of a fourth body with a mass of order 0.15 M⊙ is discussed. These third and fourth bodies could be low-mass main-sequence stars (red dwarfs).