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Helioseismic test of non-homologous solar radius changes with the 11-year activity cycle

S. Lefebvre·A. G. Kosovichev·J. P. Rozelot
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Abstract

Recent models of variations of the Sun's structure with the 11-year activity cycle by Sofia et al (2005) predict strong non-homologous changes of the radius of subsurface layers, due to subsurface magnetic fields and field-modulated turbulence. According to their best model the changes of the surface radius may be 1000 times larger than those at the depth of 5 Mm. We use f-mode oscillation frequency data from the MDI instrument of Solar and Heliospheric Observatory (SOHO) and measurements of the solar surface radius variations from SOHO and ground-based observatories during solar cycle 23 (1996-2005) to put constraints on the radius changes. The results show that the above model overestimates the change of the radius at the surface relative to the change at 5Mm.

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S. Lefebvre, A. G. Kosovichev, J. P. Rozelot. 2007-02-19. Helioseismic test of non-homologous solar radius changes with the 11-year activity cycle. https://doi.org/10.1086/515394

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