Fine-Scale Magnetic Effects on p-Modes and Higher Frequency Acoustic Waves in a Solar Active Region
Fine-Scale Magnetic Effects on p-Modes and Higher Frequency Acoustic Waves in a Solar Active Region
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太阳活动区 p 模式和高频声波的精细磁效应
DOI：
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发表时间：
2000
期刊：
影响因子：
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通讯作者：
Donald C. H. Stanchfield II
中科院分区：
文献类型：
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作者：
J. H. Thomas;Donald C. H. Stanchfield II
我们展示了快速演变的太阳活动区域的光球层和色球层在精细空间尺度上的振荡的 5 小时时间序列同步高分辨率测量结果，并检查了它们与矢量磁场的关系。光球振荡由塞曼不敏感谱线 Fe I 557.6 nm 中的多普勒频移确定，而色球振荡由 Ca II K 线中可见的强度波动确定。时间序列测量之前和之后的矢量磁场配置是通过 Fe I 630.15 和 630.25 nm 线剖面的全斯托克斯反演获得的。在光球层和色球层中，p 模功率受到磁场的抑制，随着场强的增加而降低。在较高频率（高于声截止），功率在光球层和色球层的最高磁场强度处也受到抑制，但在光球层中最高场强斑块周围的中间场强局部斑块（“光晕”）中功率得到增强（如 Brown 等人首先报道的）。色球层中存在类似光环的证据（如 Braun 等人和 Toner & LaBonte 首次发现的）及其与光球光环的关联尚不清楚。我们发现了地震证据，表现为抑制 p 模式和高频功率以及增强高频功率的晕环，在 Fe I 557.6 nm 核心强度中以暗斑形式出现之前存在发育中的孔隙。该结果表明，p 模功率抑制不能主要归因于较冷孔隙大气的透明度较高。
We present results from a 5 hr time series of simultaneous high-resolution measurements of oscillations in the photosphere and the chromosphere on fine spatial scales for a rapidly evolving solar active region and examine their relation to the vector magnetic field. The photospheric oscillations are determined from Doppler shifts in the Zeeman-insensitive spectral line Fe I 557.6 nm, whereas the chromospheric oscillations are determined from the intensity fluctuations seen in the Ca II K line. The vector magnetic field configurations just prior to and just after the time-series measurements are obtained from the full Stokes inversion of the line profiles of Fe I 630.15 and 630.25 nm. In both the photosphere and the chromosphere, p-mode power is suppressed by the magnetic field, decreasing with increasing field strength. At higher frequencies (above the acoustic cutoff) power is also suppressed at the highest magnetic field strengths in the photosphere and the chromosphere but is enhanced in the photosphere in localized patches ("halos") of intermediate field strength surrounding the patches of highest field strength (as first reported by Brown et al.). The evidence for similar halos in the chromosphere (as first seen by Braun et al. and Toner & LaBonte) and their association with the photospheric halos is less clear. We find seismic evidence, in the forms of suppression of p-mode and higher frequency power and a halo of enhanced higher frequency power, for a developing pore prior to its appearance as a dark patch in Fe I 557.6 nm core intensity. This result shows that p-mode power suppression cannot be due primarily to the greater transparency of the cooler pore atmosphere.