Re: What's the most famous and biggest (in size) neutron star?

An interesting question Justin. What makes a Neutron star "famous". As I am sure you know, Neutron Stars are left over after a Red-Giant Star like Betelgeuse or Aldebaran explodes as a Supernovae. They are small, typically not bigger than about 30 km or 20 miles across, and not bright enough to see in a telescope. When created, Neutron Stars start spinning with great speed, between three times a second to one thousand times a second. They also give off two beams of radio waves, like a light house. These are called Pulsars. So, the question I will answer is, what is the most famous Pulsar?

Back in 1967 a group of Astronomers from Cambridge, England where looking at the Universe with Telescopes designed to measure radio waves, not visible light. To their surprise they detected a signal that repeated itself every three and two thirds of a second (11/3 s^-1) , exactly. This was found by Professor S. Jocelyn Bell Burnell and her boss Tony Hewish. Because the radio signal repeated itself so accurately, and nothing known in Astronomy was that regular, it was suggested this was an Alien culture trying to tell others they existed. We now know this was a Pulsar, not Aliens. This Pulsar (Neutron Star) became famous overnight as a possible Alien culture trying to signal others. This Pulsar goes by the totally forgettable name of PSR1915+21

Another possibility is the Pulsar PSR1913+16. This was used to check Albert Einsteins theory of General Relativity. So it provides one of the tests that Relativity is correct.

Your other question is which Neutron Star is the Biggest? This is harder to answer as many Pulsars (Neutron Stars) have been found and not all have been measured for size. It is thought that any star whose core is slightly more massive than our Sun will turn into a Black Hole. This means that the Star itself is many times bigger than our Sun. So, no Neutron Star should be more massive than, about, one and half times the mass of our Sun. This means the largest size of any Neutron Star is about 40Km, or about 30 miles.

Further information on this can be found in the following links,

• Jocelyn Bells' own words on how pulsars where found
• Who found what when
• University Lecture notes about this

My personal thanks to Prof. S. Jocelyn Bell Burnell (Open University) for providing information on the names of these pulsars and the importance of PSR1913+16, which I had never heard of before, in Science.