Abstract

For both periods of the double-mode Cepheid V371 Per and for the Cepheid OGLE-LMC-CEP-2132 we have constructed \(O-C\) diagrams spanning a time interval of 126 and 119 years, respectively. The \(O-C\) diagrams have the shape of parabolas, which has allowed us for the first time to determine the quadratic light elements and to calculate the rates of evolutionary changes in their periods: \(dP_{Fu}/dt=1.085({\pm}{0.007})\) s yr\({}^{-1}\) and \(dP_{1O}/dt=0.923({\pm}{0.003})\) s yr\({}^{-1}\) for the fundamental mode and the first overtone of V371 Per, respectively, and \(dP/dt=15.304({\pm}{0.048})\) s yr\({}^{-1}\) for OGLE-LMC-CEP-2132, in agreement with the results of theoretical calculations for the first crossing of the instability strip. The pulsation stability test proposed by Lombard and Koen has confirmed that the increase in the periods is real.

中文翻译：

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造父变星 V371 Per 和 OGLE-LMC-CEP-2132：第一次穿越不稳定带

摘要

对于双模造父变星 V371 Per 和造父变星 OGLE-LMC-CEP-2132 的两个时期，我们分别构建了跨越 126 年和 119 年时间间隔的OC图。\ (OC\)图具有抛物线形状，这使我们第一次能够确定二次轻元素并计算其周期内的进化变化率：\( dP_{Fu}/dt=1.085( {\pm}{0.007})\) s 年\({}^{-1}\)和\(dP_{1O}/dt=0.923({\pm}{0.003})\) s 年\({ }^{-1}\)分别表示 V371 Per 的基模和第一泛音，\(dP/dt=15.304({\pm}{0.048})\) s yr \({}^{- 1}\)对于OGLE-LMC-CEP-2132，与第一次穿越不稳定带的理论计算结果一致。Lombard 和 Koen 提出的脉动稳定性试验证实了周期的增加是真实的。