Lecture 24 - Binary Neutron Stars

In 1974, a binary neutron star system was discovered - two neutron stars going around a common centre of mass. Russel Hulse, a young PhD student working under the supervison of Joseph Taylor, had been at the center of this discovery which gave us the first evidence (albeit indirect) of Gravitational Waves! This lecture describe neutron star binaries of different types and their signficance for Einstein's General Theory of Relativity.

In 1974, a binary neutron star system was discovered - two neutron stars going around a common centre of mass. This raised the following question: ""How did such a system form?"" The first part of this lecture is devoted to the evolution of massive stars in 'binary systems', and the eventual formation of a bound pair of neutron stars.
The separation of the two neutron stars was a mere million kilometres, roughly the radius of the Sun. With two massive objects in such a tight binary, General Relativistic effects were expected to be large in comparison to the GR effects, say, on the orbit of Mercury. Indeed they were! The second part of this lecture will describe the various relativistic effects that were verified to unprecedented accuracy using this system. Observations of this system also provided the very first evidence for Gravitational Radiation. Not surprisingly, the Nobel Prize was awarded to Hulse and Taylor, who discovered this pulsar, and demonstrated the existence of gravitational radiation.