Testing the Constancy of the Gravitational Constant Using Helioseismology
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Abstract
We compare the p-mode oscillation spectra of solar models, constructed under the assumption that the universal gravitation constant G varied monotonically over the course of the solar lifetime, to the most recent solar p-mode frequency observations from the Global Oscillation Network Group (GONG) instrument and Birmingham Solar Oscillation Network (BiSON). The GONG instrument consists of six telescopes spread over different longitude around the Earth, each recording, once every minute, Doppler shift images of the Sun's surface. BiSON also consists of a network of six telescopes specifically designed to observe low-l p-modes. We find that only those solar models constructed with (1/G)dG/dt ≤ ~1.6 × 10-12 yr-1 are consistent with the observations. This constraint not only probes G over cosmic time, it is stronger by almost one order of magnitude than constraints on the current maximum time variation coming from radar ranging and binary pulsar timing measurements.