An alternative explanation for the observed variation of solar p-modes with the solar cycle

Abstract

By mimicking the effects of a magnetic field on the interior structure of a solar model, observed changes in p-mode frequencies over the course of the solar cycle are explained in terms of a change in the intensity and distribution of a magnetic field near the top of the solar convection zone; previous attempts of explain these observations have concentrated on magnetic fields extending into the solar atmosphere. Specifically, the observed frequency changes for the 5 [less than or equal to] l [less than or equal to] 60 modes between 1986 and 1989 can be accounted for by a change in magnetic field strength of 400 G approximately 320 km below the solar surface; in a standard solar model, this depth corresponds to a temperature of 10,800 K and a pressure of 3.63 3 X 10[superscript 5] dyn cm[superscript -2]. These results are discussed in light of a measured change in the solar radius of 4 km between 1992 and 1994 by the Solar Disk Sextant Experiment.