Abstract—Observations of facular areas of the Sun using the Helioseismic and Magnetic Imager device of the Solar Dynamics Observatory allow detecting long-period oscillations in the magnetic field of facular knots with periods ranging from 30 to 250 minutes. Statistically significant oscillation modes are selected by the method of time series decomposition in empirical modes. During the observation period, which is close to the knot’s lifetime, its parameters (magnetic field, area on the magnetogram, etc.) may change noticeably, although the facular formation retains its structural identity all this time. These changes also affect the effective rigidity of the system (response to external disturbances), which leads to a change in the nature of the oscillations themselves. Based on this, we consider the observed oscillation in the magnetic field of facular knots with periods from 1 to 4 hours as the proper small oscillations of a system whose effective rigidity changes over time. A simple analytical model of the process is presented. It is shown that all three specific modes of low-frequency oscillations detected in facular knots are well described by the proposed model.

中文翻译：

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太阳眼结的长期振荡

摘要-使用太阳动力学天文台的Helioseismic和Magnetic Imager装置观察太阳的眼睛区域，可以检测到30到250分钟不等的眼结磁场的长期振荡。具有统计意义的振荡模式是通过经验模式中的时间序列分解方法选择的。在接近结的寿命的观察期间，尽管小孔地层一直保持其结构特征，但其参数（磁场，磁图上的面积等）可能会发生明显变化。这些变化还会影响系统的有效刚度（对外部干扰的响应），从而导致振荡本身的性质发生变化。基于此，我们将观察到的，在1到4个小时的时间周期内的共聚焦磁场中的振荡视为系统的适当小振荡，其有效刚度会随时间变化。介绍了该过程的简单分析模型。结果表明，所提出的模型很好地描述了在眼结中检测到的低频振荡的所有三种特定模式。