This work presents the first long-term photometric variability survey of the intermediate-age open cluster NGC 559. Time-series V band photometric observations on 40 nights taken over more than three years with three different telescopes are analyzed to search for variable stars in the cluster. We investigate the data for the periodicity analysis and reveal 70 variable stars including 67 periodic variables in the target field, all of them are newly discovered. The membership analysis of the periodic variables reveal that 30 of them belong to the cluster and remaining 37 are identified as field variables. Out of the 67 periodic variables, 48 are short-period (P 1 day) variables. The variable stars have periodicity between 3 hours to 41 days and their brightness ranges from V = 10.9 to 19.3 mag. The periodic variables belonging to the cluster are then classified into different variability types on the basis of observational properties such as shape of the light curves, periods, amplitudes, as well as their positions in the Hertzsprung-Russell (H-R) diagram. As a result, we identify one Algol type eclipsing binary, one possible blue straggler star, 3 slowly pulsating B type stars, 5 rotational variables, 11 non-pulsating variables, 2 FKCOM variables and remaining 7 are characterized as miscellaneous variables. We also identify three Eclipsing Binary stars (EBs) belonging to the field star population. The PHOEBE package is used to analyse the light curve of all four EBs in order to determine the parameters of the binary systems such as masses, temperatures and radii.

中文翻译：

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中年疏散星团NGC 559领域的变星

这项工作展示了中年疏散星团 NGC 559 的首次长期光度变化调查。 分析了使用三台不同望远镜在三年多时间里对 40 个夜晚进行的时间序列 V 波段光度观测，以寻找星团中的变星。簇。我们调查了周期性分析的数据，在目标场中揭示了 70 颗变星，其中包括 67 个周期变量，它们都是新发现的。周期变量的隶属度分析表明，其中 30 个属于该类群，其余 37 个被识别为字段变量。在 67 个周期变量中，48 个是短期（P 1 天）变量。变星的周期在 3 小时到 41 天之间，它们的亮度范围从 V = 10.9 到 19.3 mag。然后，根据光变曲线的形状、周期、振幅以及它们在赫兹-罗素 (HR) 图中的位置等观测特性，将属于该类群的周期变量分为不同的可变性类型。结果，我们确定了一颗 Algol 型食双星、一颗可能的蓝色落后星、3 颗缓慢脉动的 B 型恒星、5 个旋转变星、11 个非脉动变星、2 个 FKCOM 变星，其余 7 个被表征为杂变星。我们还确定了属于场星群的三颗食双星 (EB)。PHOEBE 包用于分析所有四个 EB 的光变曲线，以确定二元系统的参数，如质量、温度和半径。