p Modes in and Away from a Sunspot
p Modes in and Away from a Sunspot
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p 太阳黑子内和远离太阳黑子的模态
DOI：
10.1023/a:1005209623215
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发表时间：
1999
期刊：
影响因子：
2.8
通讯作者：
M. R. Deshpande
中科院分区：
文献类型：
--
作者：
B. Kumar;R. Jain;S. Tripathy;H. Vats;M. R. Deshpande
利用1997年5月10-14日Udaipur站和Big Bear站的GONG多普勒时间序列，同时测量了太阳黑子（NOAA活动区8038）和平静光球的速度起伏。我们观察到，占主导地位的p模式的功率在太阳黑子相比，安静的光球减少了39-52%，这取决于太阳黑子区域在太阳盘面上的位置。我们还观察到黑子中p模的相对峰值频率偏差为80-310 μHz，它与活动区的磁场梯度呈线性关系。5月12日的最大频率偏差为310 μHz，这似乎是在该活动区发生的长时间太阳耀斑的影响。我们解释这种相对峰值频率偏差是由于功率重新分布的p模式在太阳黑子或这些模式的频率调制的后果沿着磁通量管由于快速变化的磁场结构。
A time series of GONG Dopplergrams for the period 10–14 May 1997 from Udaipur and Big Bear sites has been used to measure the velocity fluctuations in a sunspot (NOAA active region 8038) and quiet photosphere simultaneously. We observe that the power of pre-dominant p mode is reduced in the sunspot as compared to quiet photosphere by 39–52% depending on the location of the sunspot region on the solar disk. We also observe a relative peak frequency deviation of p modes in the sunspot, of the order of 80–310 μHz, which shows a linear dependence on the magnetic field gradient in the active region. The maximum frequency deviation of 310 μHz on 12 May appears to be an influence of a long-duration solar flare that occurred in this active region. We interpret this relative peak frequency deviation as either due to power re-distribution of p modes in the sunspot or a consequence of frequency modulation of these modes along the magnetic flux tubes due to rapidly varying magnetic field structure.