The Gravitational Constant, the Chandrasekhar Limit, and Neutron Star Masses

The Chandrasekhar mass limit sets the scale for the late evolutionary stages of massive stars, including the formation of neutron stars in core collapse supernovae. Because its value depends on the gravitational constant G, the masses of these neutron stars retain a record of past values of G. Using Bayesian statistical techniques, I show that measurements of the masses of young and old neutron stars in pulsar binaries limit \dot G/G=(-0.6 \pm 2.0) x 10^-12 yr^-1 (68% confidence) or \dot G/G=(-0.6 \pm 4.2) x 10^-12 yr^-1 (95% confidence).