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#### Simulation of a spherical magneto-acoustic wave propagating in the solar atmosphere: interaction with magnetic canopy, $\delta v$

Author: Christian Nutto
Affiliation: Kiepenheuer-Institut für Sonnenphysik, Freiburg, Germany

Co-authors: M. Roth, O. Steiner

Main category: Natural Sciences (Astronomy)

Caption:
The spherical magneto-acoustic wave is excited right beneath the magnetic canopy. The color map shows the velocity perturbations $\delta |v|$. The green contours display the equipartition level, where $c_\mathrm{s} =c_\mathrm{A}$.

Further information:
The canopy stems from the magnetic flux concentration that is vertically expanding nearby. In velocity perturbations, both modes of the magneto-acoustic wave, the fast and the slow mode, can be followed at once, because both modes introduce perturbations in the velocity. A characteristic criterion for the slow
acoustic mode in the low $\beta$ regime is that velocity and pressure perturbations propagate
along the magnetic field lines.

Further Reading: Dissertation: Numerical experiments on the propagation of waves in a convectively unstable magneto-atmosphere: A new interpretation of the measured reduction of wave travel-times in magnetic regions of the Sun. (Figure 5.3)