Deakin University
Browse
shelyag-photospherichigh-2013.pdf (1.34 MB)

Photospheric high-frequency acoustic power excess in sunspot umbra: signature of magneto-acoustic modes

Download (1.34 MB)
journal contribution
posted on 2013-01-01, 00:00 authored by S Zharkov, Sergiy ShelyagSergiy Shelyag, V Fedun, R Erdélyi, M J Thompson
We present observational evidence for the presence of MHD (magnetohydrodynamic) waves in the solar photosphere deduced from SOHO/MDI (Solar and Heliospheric Observatory/Michelson Doppler Imager) Dopplergram velocity observations. The magneto-acoustic perturbations are observed as acoustic power enhancement in the sunspot umbra at high-frequency bands in the velocity component perpendicular to the magnetic field. We use numerical modelling of wave propagation through localised non-uniform magnetic field concentration along with the same filtering procedure as applied to the observations to identify the observed waves. Guided by the results of the numerical simulations we classify the observed oscillations as magneto-acoustic waves excited by the trapped sub-photospheric acoustic waves. We consider the potential application of the presented method as a diagnostic tool for magnetohelioseismology.

History

Journal

Annales geophysicae

Volume

31

Issue

8

Pagination

1357 - 1364

Publisher

Copernicus Publications on behalf of the European Geosciences Union

Location

Göttingen, Germany

ISSN

0992-7689

eISSN

1432-0576

Language

eng

Publication classification

C1.1 Refereed article in a scholarly journal

Copyright notice

2013, Author(s)