Pulsar

A black widow lurks 3000 light years away Space

A black widow lurks 3000 light years away

Astronomers love analogies from the animal kingdom. For a fast rotating neutron star, which feeds on its life partner, they have coined the term "black widow", although neutron stars are of course neither black nor widows. The star from which these pulsars (which otherwise would quickly come to rest on an astronomical scale) draw fresh energy for their rotation is still alive. Normally, such systems - about two dozen are known in the Milky Way alone - are identified by the X-rays and gamma rays that the pulsars emit like celestial lighthouses. However, not every pulsar also radiates in…
Pulsars: of black widows and redback spiders Astrophysics

Pulsars: of black widows and redback spiders

Double-star systems end like many marriages: one of the partners almost always dies before the other. When a star dies, if it was not too large, all that remains is a neutron star. This contains a big portion of the mass of the original star, but has a diameter of only about 20 kilometers (12.4 miles). So, like a figure skater who pulls in her arms to spin faster, the neutron star must rotate very quickly about its axis. In doing so, it emits radio waves like a lighthouse – for astronomers it becomes a pulsar, because the radio…