Neutron Star Packs Two Suns' Mass in Size of City

Astronomers have discovered what they say is the mightiest neutron star yet. The super-dense object, which lies some 3,000 light-years from Earth, is about twice as massive as our Sun. That is 20% greater than the previous record holder, the US-Dutch team behind the observation tells the journal Nature. "It's approximately the size of a city, which for an astronomical object is interesting because people can conceive of it pretty easily," the study's lead author told BBC News.

The finding is important, says Dr Demorest's team, because it puts constraints on the type of exotic material that can form a neutron star. Such objects are thought to be the remnant cores of once giant stars that blew themselves apart at the ends of their lives. As well being fantastically compact, the cores also spin incredibly fast. This particular object, classified as PSR J1614-2230, revolves 317 times a second. It is what is termed a pulsar - so-called because it sends out lighthouse-like beams of radio waves that are seen as radio "pulses" every time they sweep over the Earth.