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Recently discovered properties of acoustic power

Auteur

Schunker Hannah

Institution

Max Planck Institut fur Sonnensystemforschung

Theme

Local helioseismology
Auteur(s) supplémentaire(s)D.C. Braun
Institution(s) supplémentaire(s)NorthWest Research Assoc., CoRA Division

Abstract

In the presence of surface magnetic fields, spatial variations in surface acoustic power are noticeable, although their cause is not as yet clear. We present recently discovered properties of the enhanced acoustic power observed using MDI over seven days and multiple active regions, including AR 9787.
We find
i) a strong correlation of the enhanced high frequency power
with intermediate strength, horizontal magnetic-fields,
ii) the frequency of the maximum enhancement increases with magnetic field strength, and
iii) the oscillations contributing to the halos show mode ridges in the power spectrum shifted to higher wave number at constant frequency in comparison to the quiet-Sun mode ridges. Modelling these observations will help to discern the physical cause of the acoustic power variations, and help interpret helioseismic observations of magnetic fields.
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