The 42-foot-diameter Jodrell Bank telescope has been observing the Crab pulsar, a neutron star that formed in a massive cosmic explosion seen in both Europe and China in A.D. 1054 as a bright star in the daytime sky. Only about 15 miles across but containing the mass of nearly 1 million Earths, the pulsar is rotating 30 times a second, emitting beams of radio waves that, like a lighthouse, produce flashes each time it rotates.
Researchers at the University of Manchester say a 22-year study of the pulsar has recorded a steady change in the flashes, yielding clues about its strong magnetic field and its otherwise-inaccessible interior.
The interval between flashes is slowing down by a minute amount, suggesting the pulsar's magnetic field is slowly moving from its poles toward its equator, the scientists said.
It's a surprising finding, the said, because he interior of the star is superconducting and the magnetic field should be frozen in position.
"This pulsar is just 960 years old, so while 22 years gives only a small sample of its lifetime, it is a much larger fraction of a stellar lifetime than astronomers usually get to study," study co-author Sir Francis Graham Smith said.
The findings will have important implications for understanding the evolution of pulsars and how they emit energy, the researchers said.