Astron. Nachrichten 328, 323 (2007)
Proceedings of the First HELAS Local Helioseismology Workshop "Roadmap for European Local Helioseismology", Nice, 2006:

Oskar Steiner (Kiepenheuer-Institut für Sonnenphysik, Schöneckstrasse 6, 79104 Freiburg, Germany)
G. Vigeesh (Indian Institute of Astrophysics, Koramangala, Bangalore 560034, India)
Lars Krieger (Kiepenheuer-Institut für Sonnenphysik, Schöneckstrasse 6, 79104 Freiburg, Germany / Indian Institute of Astrophysics, Koramangala, Bangalore 560034, India)
Sven Wedemeyer-Böhm (Institute of Theoretical Astrophysics, Postboks 1029 Blindern, 0315 Oslo, Norway)
Werner Schaffenberger (Kiepenheuer-Institut für Sonnenphysik, Schöneckstrasse 6, 79104 Freiburg, Germany)
Bernd Freytag (Centre de Recherche Astronomique de Lyon - Ecole Normale Superieure, 46, Allee d'Italie, F-69364 Lyon Cedex 07, France)

First local helioseismic experiments with CO5BOLD


With numerical experiments we explore the feasibility of using high frequency waves for probing the magnetic fields in the photosphere and the chromosphere of the Sun. We track a plane-parallel, monochromatic wave that propagates through a non-stationary, realistic atmosphere, from the convection-zone through the photosphere into the magnetically dominated chromosphere, where it gets refracted and reflected. We compare the wave travel time between two fixed geometrical height levels in the atmosphere (representing the formation height of two spectral lines) with the topography of the surface of equal magnetic and thermal energy density (the magnetic canopy or beta=1 contour) and find good correspondence between the two. We conclude that high frequency waves indeed bear information on the topography of the `magnetic canopy'.


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