About three times a second, a 10,000-year-old stellar corpse sweeps a beam of gamma-rays toward Earth. Just discovered by NASA’s Fermi Gamma-ray Space Telescope, the object, called a pulsar, is the first one known that “blinks” in pure gamma rays.The gamma-ray-only pulsar lies within a supernova remnant known as CTA 1 located about 4,600 light-years away in the constellation Cepheus. Its lighthouse-like beam sweeps Earth’s way every 316.86 milliseconds. The pulsar, which formed in a supernova explosion about 10,000 years ago, emits 1,000 times the energy of our sun.
The pulsar in CTA 1 is not located at the center of the supernova’s expanding gaseous shell. Supernova explosions can be asymmetrical, often imparting a “kick” that sends the neutron star careening through space. Based on the remnant’s age and the pulsar’s distance from its center, astronomers believe the neutron star is moving at about a million miles per hour — a typical speed for neutron stars.
Fermi’s Large Area Telescope scans the entire sky every three hours and detects photons with energies ranging from 20 million to more than 300 billion times the energy of visible light.