The sun as a probe of varying G

In order to explore the ability of helioseismology and features of solar models to test the constancy of the gravitational constant G during the last 4.5 Gyr of solar evolution, we have constructed a grid of evolutionary sequences for solar models under the assumptions that G varies with time, and have explored the sensitivity of their nonradial acoustic mode oscillation spectra to G variability. All final models satisfy the standard constraints for the present Sun and, except for the variation in G, were constructed under the assumptions of a standard solar model. When compared with the observed solar p-mode spectrum, our models definitely rule out β > 0.4 and β < -0.4, where G(t) ∝ t^-β over the last 4.5 Gyr. These limits can be tightened to rule out |β| > O(0.1) by the use of other solar observables. For nonmonotonic variation in G this suggests that longtimescale variations greater than O(5%) in G are ruled out over the last 4.5 Gyr. Future prospects for improving the sensitivity of helioseismic tests of a varying G are also discussed. Finally, we explore the sensitivity of the predicted solar neutrino flux to varying G.