Journal
ASTRONOMY & ASTROPHYSICS
Volume 525, Issue -, Pages -Publisher
EDP SCIENCES S A
DOI: 10.1051/0004-6361/200913533
Keywords
sunspots; Sun: oscillations; Sun: chromosphere; Sun: photosphere
Categories
Funding
- Royal Society [10-02-00153-a]
- Federal Agency for Science and Innovation [02.740.11.0576]
- [RFBR 08-02-91860-KO_a]
- EPSRC [EP/H02395X/1, EP/D062837/1] Funding Source: UKRI
- STFC [ST/F00205X/1] Funding Source: UKRI
- Engineering and Physical Sciences Research Council [EP/H02395X/1, EP/D062837/1] Funding Source: researchfish
- Science and Technology Facilities Council [ST/F00205X/1] Funding Source: researchfish
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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.
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