Lecture 18 - Supernovae and Neutron Stars

On July 4, 1054, Chinese and Japanese astronomers observed a new, bright `guest star' in the constellation of Taurus which could be seen even during the daytime. Many ancient cultures recorded the event, including the Anasazi Indians (in present-day Arizona and New Mexico) as have been found in the ancient pictographs made by them.

Modern scientists identify this `guest star' as a supernova explosion and its remnant, the Crab Nebula, happens to be the first astronomical object to be associated with a historical supernova explosion. Not surprisingly, the Crab Nebula also occupies a rather central position in the development of our understanding of the physics of supernovae and neutron stars.

In the 1940, Dutch historians and astronomers made the remarkable identification of the “Crab Nebula”, in the constellation Taurus, with the expanding debris of the Chinese “Guest Star” that exploded in 1054 AD. In the 1950s, a Russian astrophysicist advanced the revolutionary idea that the X-ray, optical and radio radiation we observe from the Crab Nebula must be “synchrotron radiation” from relativistic particles gyrating in the magnetic field of the nebula, both being produced by a “central engine” in the nebula. In 1967, a young Italian conjectured that this ‘central engine’ could be a rapidly spinning, strongly magnetized Neutron Star. A few months later, precisely such a neutron star was discovered at the dynamical centre of the Crab Nebula. This lecture is devoted to this remarkable story.