ASTRONOMERS have identified the smallest known black hole – a dark void in space-time only about 20 kilometres wide. They have also found four unusually heavy neutron stars, and together these objects are plugging a mysterious gap in the range of masses of dead stars that roam our galaxy.
The discovery of these “missing links” has delighted astronomers. “It’s reassuring because there is no physical reason that these things shouldn’t be there,” says David Nice of Princeton University in New Jersey. “This has been quite a puzzle.”
Both neutron stars and black holes form when very massive stars blow up in…
