标题： NGC 4147中RR lyrae变星的长期周期变化 显示英文标题

标题： Secular period variations of RR Lyrae stars in NGC 4147

摘要： 对NGC 4147的测光时序数据进行了长达58年的编译，这使得可以研究该星团中造父变星群体的脉动周期的长期行为。 采用了传统的O-C图方法。 三颗星显示出显著的周期减小，而两颗星则表现出相当的周期增加。 然而，整个样本的中位数几乎为零，这似乎与理论预期一致。 讨论了使用经验方法确定球状星团中恒星周期变化的局限性，以及如何验证演化理论预测。 显示英文摘要

摘要： A compilation of photometric time-series data of NGC 4147 spanning 58 years, enabled to study the secular behaviour of the pulsation period in the population of RR Lyrae stars in the cluster. The traditional O-C diagram approach was employed. Three stars display a significant period decrease and two a comparable period increase. Nevertheless, the median value of the whole sample is nearly zero, which seems consistent with theoretical expectations. The limitations of empirical determinations of secular period changes in globular clusters to corroborate evolutionary theoretical predictions are discussed.