Propagating waves and magnetohydrodynamic mode coupling in the quiet-sun network

被引:24
作者
Bloomfield, DS [1 ]
McAteer, RTJ
Mathioudakis, M
Williams, DR
Keenan, FP
机构
[1] Queens Univ Belfast, Dept Pure & Appl Phys, Belfast BT7 1NN, Antrim, North Ireland
[2] UCL, Mullard Space Sci Lab, Dorking RH5 6NT, Surrey, England
关键词
MHD; Sun : chromosphere; Sun : magnetic fields; Sun : oscillations; Sun : photosphere;
D O I
10.1086/382062
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
High-cadence multiwavelength optical observations were taken with the Dunn Solar Telescope at the National Solar Observatory, Sacramento Peak, accompanied by Advanced Stokes Polarimeter vector magnetograms. A total of 11 network bright points (NBPs) have been studied at different atmospheric heights using images taken in wave bands centered on Mg I b(1) - 0.4 Angstrom, Halpha, and Ca II K-3. Wavelet analysis was used to study wave packets and identify traveling magnetohydrodynamic waves. Wave speeds were estimated through the temporal cross-correlation of signals, in selected frequency bands of wavelet power, in each wavelength. Four mode-coupling cases were identified, one in each of four of the NBPs, and the variation of the associated Fourier power with height was studied. Three of the detected mode-coupling, transverse-mode frequencies were observed in the 1.2-1.6 mHz range (mean NBP apparent flux density magnitudes over 99-111 Mx cm(-2)), with the final case showing 2.0-2.2 mHz (with 142 Mx cm(-2)). Following this, longitudinal-mode frequencies were detected in the range 2.6-3.2 mHz for three of our cases, with 3.9-4.1 mHz for the remaining case. After mode coupling, two cases displayed a decrease in longitudinal-mode Fourier power in the higher chromosphere.
引用
收藏
页码:936 / 943
页数:8
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