Just heard this on the podcast “Mountain Radio Astronomy”. Their podcast of 8 October 2005 was an interview with pulsar hunter Scott Ransom at the National Radio Astronomy Observatory in Charlottesville. Scott had – at the time of the interview – found about 30 millisecond pulsars in a globular star cluster called Terzan 5.

A pulsar is believed to be a quickly rotating neutron star, a supernova remnant, most of them rotating in less than a second. The pulsar has a rather small and directional radiating area that can only be registered when it is facing us.
A second type of even faster rotating pulsars – known as millisecond pulsars – rotating more than a 100 tomes per second, are found in globular star clusters.

The rotation period of the millisecond pulsars is extremely precise, approaching that of an atomic clock , and this means thatsome interesting measurements of pulsar orbits can be made.

About 20 minutes into the interview he talked about a measurement of a pulsar orbit with an accuracy that really surprised me.

The example here is the Hulse-Taylor star system two pulsars orbiting each other in an orbit smaller than the Sun.This can demonstrate Einstein’s general theory of relativity, the interaction between spacetime and gravitation and an indication of gravity waves.

One other of the pulsars, Terzan N is orbiting a massive companion in an almost exact circular orbit about the size of the Sun.there is a little eccentricity, that is difference in the long axis and the short axis of the orbit, is measured as 48 cm +/- 6 cm. Less than half a meter ! Measured at a distance of 20 000 light years. Mind blowing …

Science stranger than fiction …

Link to Mountain Radio Astronomy

Link to The podcast MP3 file