Period change and δ Scuti pulsations of eclipsing binary star RZ Cassiopiae

Abstract

RZ Cas is an Algol-type partial eclipsing binary, the secondary component of which has filled its Roche lobe. Its visual magnitude is 6.18 and its period is 1.195 days. The most important characteristics of RZ Cas are period change (due to mass transfer) and anomalies in the primary minimum of its light curve (due to δ Scuti pulsations). In this paper, light curves of RZ Cas are obtained using the Johnson's U, B, V, and R filters at Isfahan University Observatory, and B and V filters at Biruni Observatory of Shiraz University. Continuous photometric measurements have also been made to detect δ Scuti type pulsations. A new ephemeris and period is obtained: Min.I =HJD2453620.5500 + 1d.1952639 E, and a mass transfer rate of 1.5×10 -7 M⊙ yr -1 is estimated. None of the observed primary minima is flat as found by some observers before. The residuals from the observed minus computed light curves of the system give the pulsation light curves of the primary component. The frequencies of δ Scuti pulsation are searched for using the Period04 program. It is found that the dominant frequency is 65.5-68.5 cycle/day, corresponding to a period of 21-22 min.

Keywords

• stars
• binaries
• eclipsing – stars
• oscillations
• δ scuti type – stars
• individual
• RZ Cas – eclipsing binaries
• change of period