ON THE PROPERTIES OF SLOW MHD SAUSAGE WAVES WITHIN SMALL-SCALE PHOTOSPHERIC MAGNETIC STRUCTURES
ON THE PROPERTIES OF SLOW MHD SAUSAGE WAVES WITHIN SMALL-SCALE PHOTOSPHERIC MAGNETIC STRUCTURES
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DOI：
10.3847/0004-637x/817/1/44
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发表时间：
2015-09
期刊：
影响因子：
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通讯作者：
N. Freij;I. Dorotovic;R. Morton;M. Ruderman;M. Ruderman;V. Karlovský;R. Erdélyi;R. Erdélyi
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文献类型：
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作者：
N. Freij;I. Dorotovic;R. Morton;M. Ruderman;M. Ruderman;V. Karlovský;R. Erdélyi;R. Erdélyi
磁声波在太阳大气中的磁结构中的存在是有据可查的。应用太阳磁震学（SMS）技术，使我们能够推断这些结构的背景属性。在这里，我们的目标是确定所观察到的磁声波的性质，并研究低层太阳大气中的磁结构的背景特性。利用荷兰开放望远镜和太阳大气中的快速振荡仪器，我们捕获了两个系列的高分辨率强度图像，其中两个孤立的磁孔有很短的节奏。结合小波分析和经验模态分解（EMD），我们确定了横截面内的特征周期（即，时间序列和强度序列。然后，应用线性磁流体力学（MHD）理论，我们确定了这些振荡的MHD框架内的模式。在这两个磁孔内检测到几个振荡。它们的周期从3到20分钟不等。结合小波分析和EMD使我们能够自信地找到面积和强度振荡之间的相位差。从这些观察到的特征，我们得出结论，检测到的振荡可以归类为慢香肠MHD波。此外，我们确定了这些振荡的几个关键属性，如径向速度扰动，磁场扰动，和垂直波数使用SMS。相关波数的估计范围表明，这些振荡被困在这些磁性结构中。我们的研究结果表明，检测到的振荡是驻谐波，这使我们能够估计的扩展因子的波导采用SMS。计算的膨胀系数范围为4至12。
The presence of magnetoacoustic waves in magnetic structures in the solar atmosphere is well-documented. Applying the technique of solar magneto-seismology (SMS) allows us to infer the background properties of these structures. Here, we aim to identify properties of the observed magnetoacoustic waves and study the background properties of magnetic structures within the lower solar atmosphere. Using the Dutch Open Telescope and Rapid Oscillations in the Solar Atmosphere instruments, we captured two series of high-resolution intensity images with short cadences of two isolated magnetic pores. Combining wavelet analysis and empirical mode decomposition (EMD), we determined characteristic periods within the cross-sectional (i.e., area) and intensity time series. Then, by applying the theory of linear magnetohydrodynamics (MHD), we identified the mode of these oscillations within the MHD framework. Several oscillations have been detected within these two magnetic pores. Their periods range from 3 to 20 minutes. Combining wavelet analysis and EMD enables us to confidently find the phase difference between the area and intensity oscillations. From these observed features, we concluded that the detected oscillations can be classified as slow sausage MHD waves. Furthermore, we determined several key properties of these oscillations such as the radial velocity perturbation, the magnetic field perturbation, and the vertical wavenumber using SMS. The estimated range of the related wavenumbers reveals that these oscillations are trapped within these magnetic structures. Our results suggest that the detected oscillations are standing harmonics, and this allows us to estimate the expansion factor of the waveguides by employing SMS. The calculated expansion factor ranges from 4 to 12.