Search for Evolutionary Changes in the Periods of Cepheids: V532 Cyg

Abstract

For the low-amplitude Cepheid V532 Cyg we have constructed an O − C diagram spanning a time interval of 121 years. The O − C diagram has the shape of a parabola, which has made it possible to determine for the first time the quadratic light elements and to calculate the rate of evolutionary decrease in the period, dP/dt = −0.248 (±0.067) s yr⁻¹, which points to the second crossing of the instability strip. The pulsation stability test proposed by Lombard and Koen (1993) has confirmed that the period decrease is real.