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arXiv · 1111.6676

Height distribution of the power of 3-min oscillations over sunspots

N. I. Kobanov·D. Y. Kolobov·S. A. Chupin·V. M. Nakariakov
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Abstract

Context. The height structure of 3-min oscillations over sunspots is studied in the context of the recently discovered effect of height inversion: over the umbra, the spatial location of the maximum of chromospheric 3-min oscillation power corresponds to the relative decrease in the power of photospheric oscillations. Aims. We investigate whether the height inversion of the power of 3-min oscillations is a common feature of the spatial structure of the oscillations for the majority of sunspots. Methods. Spectrogram sequences of H-alpha 6563{\AA} and FeI 6569{\AA} over sunspots, acquired with very high cadency (about 2 s or better) are obtained. The distribution of the oscillation power of the line-of-sight velocity signal is studied by using methods of wavelet frequency filtration and Fourier analysis. Results. The effect of the height inversion is found in 9 of 11 analyzed active regions. The interpretation of this effect is possibly connected to both the decrease in the level of photosphere in sunspot umbrae and the magnetic field topology.

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N. I. Kobanov, D. Y. Kolobov, S. A. Chupin, V. M. Nakariakov. 2011-11-29. Height distribution of the power of 3-min oscillations over sunspots. https://doi.org/10.1051/0004-6361/200913533

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