An Upper Limit on the Temporal Variations of the Solar Interior Stratification

Abstract

We have analyzed changes in the acoustic oscillation eigenfrequencies measured over the past 7 years by the GONG, MDI and LOWL instruments. The observations span the period from 1994 to 2001 that corresponds to half a solar cycle, from minimum to maximum solar activity. These data were inverted to look for a signature of the activity cycle on the solar stratification. A one-dimensional structure inversion was carried out to map the temporal variation of the radial distribution of the sound speed at the boundary between the radiative and convective zones. Such variation could indicate the presence of a toroidal magnetic field anchored in this region. We found no systematic variation with time of the stratification at the base of the convection zone. However we can set an upper limit to any fractional change of the sound speed at the level of $3\times 10^{-5}$.

11 pages, 5 figures, to appear in ApJ

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• A study of possible temporal and latitudinal variations in the properties of the solar tachocline
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• Solar-cycle variation of the sound-speed asphericity from GONG and MDI data 1995-2000
• Ring diagram analysis of the characteristics of solar oscillation modes in active regions
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Cited by in corpus (11)

• Global Seismology of the Sun
• Solar Cycle Related Changes at the Base of the Convection Zone
• Does solar structure vary with solar magnetic activity?
• Solar Cycle Variations of p-Mode Frequencies
• The Sun's interior structure and dynamics, and the solar cycle
• Structure of the near-surface layers of the Sun: asphericity and time variation
• Solar-cycle variation of sound speed near the solar surface
• Solar Cycle Related Changes in the Helium Ionization Zones of the Sun
• Evidence of solar-cycle related structural changes in the solar convection zone
• Solar Interior
• A devil in the detail: parameter cross-talk from the solar cycle and estimation of solar p-mode frequencies