SENSITIVITY OF SOLAR G-MODES TO VARYING G-COSMOLOGIES

The sensitivity of the solar g-mode oscillation spectrum to variabilit y in the universal gravitational constant G is described. Solar models in varying G cosmologies were constructed by evolving a zero-age main -sequence stellar model to the Sun's current age, while allowing the v alue of G to change according to the power law G(t)proportional to t(- beta), where beta congruent to G/GH and H is the Hubble constant. All solar models were constrained to the observed luminosity and radius at the current age of the Sun by adjusting the helium abundance and the mixing-length parameter of the models in the usual way for standard st ellar models. Low-l g-mode oscillation periods were calculated for eac h of the models and compared to the claimed observation of the solar g -mode oscillation spectrum by Hill and Gu (1990). If one accepts Hill and Gu's claims, then within the uncertainties of the physics of the s olar model calculation, our models rule out all but \G/GH\ < similar t o 0.05. In other words, we conclude that G could not have varied by mo re than 2% over the past 4.5 Gyr, the lifetime of the present-day Sun. This result lends independent support to the validity of the standard solar model.