Periods and stability of solar g-modes

Abstract

We consider the rotation independent (m = 0) frequencies of Hill and Gu (1988) and Henning and Scherrer (1988). Comparison with Cox, Guzik, and Kidman (CGK) frequencies shows that CGK are systematically 5.7 ± 0.7% larger. This effect may be due to the larger central density in this model (162 g cm−3) compared to the real Sun. A known systematic error of about one percent in the pressure calculated by the Iben (1965) procedure can account for the higher CGK central helium and density. A check of this increase of g-mode frequency with central density is made by calculating g-mode frequencies for a WIMP model with a central density of 210 g cm−3. This 30% density increase gives a 17% frequency increase, and implies a law with frequency increasing with the 17/30 power of the central density. Thus the 5.7% decrease of frequencies from the model to the real Sun indicates a central density decrease of about 9.7% to about 147 g cm−3. Comparison with the recent van der Raay g-mode frequencies shows that the CGK model frequencies are about 14% larger, as one would expect for these observed frequencies with a large P0 of 41.2 min.