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

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Kobanov, N. I., Kolobov, D. Y., Chupin, S. A. and Nakariakov, V. M. (Valery M.). (2011) Height distribution of the power of 3-min oscillations over sunspots. Astronomy & Astrophysics, Vol.525 . Article no. A41. ISSN 0004-6361

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Official URL: http://dx.doi.org/10.1051/0004-6361/200913533

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 Ha 6563 angstrom and Fe I 6569 angstrom 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.

Item Type:

Journal Article

Subjects:

Q Science > QB Astronomy

Divisions:

Faculty of Science > Physics

Journal or Publication Title:

Astronomy & Astrophysics

Publisher:

EDP Sciences

ISSN:

0004-6361