Bibcode
Dorotovič, I.; Erdélyi, R.; Freij, N.; Karlovský, V.; Márquez, I.
Bibliographical reference
Astronomy and Astrophysics, Volume 563, id.A12, 9 pp.
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3
2014
Journal
Citations
34
Refereed citations
33
Description
Aims: By focussing on the oscillations of the cross-sectional
area and the total intensity of magnetic waveguides located in the lower
solar atmosphere, we aim to detect and identify magnetohydrodynamic
(MHD) sausage waves. Methods: Capturing several high-resolution
time series of magnetic waveguides and employing a wavelet analysis, in
conjunction with empirical mode decomposition (EMD), makes the MHD wave
analysis possible. For this paper, two sunspots and one pore (with a
light bridge) were chosen as examples of MHD waveguides in the lower
solar atmosphere. Results: The waveguides display a range of
periods from 4 to 65 min. These structures display in-phase behaviour
between the area and intensity, presenting mounting evidence for sausage
modes within these waveguides. The detected periods point towards
standing oscillations. Conclusions: The presence of fast and slow
MHD sausage waves has been detected in three different magnetic
waveguides in the solar photosphere. Furthermore, these oscillations are
potentially standing harmonics supported in the waveguides that are
sandwiched vertically between the temperature minimum in the lower solar
atmosphere and the transition region. The relevance of standing harmonic
oscillations is that their exploitation by means of solar
magneto-seismology may allow insight into the sub-pixel resolution
structure of photospheric MHD waveguides.