Pulsar

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…