The Crab pulsar is a neutron star which formed in a massive cosmic explosion seen in both Europe and China in AD 1054 as a bright star in the daytime sky.
Now rotating 30 times a second, this highly-compact star emits beams of radio waves that, like a lighthouse, produce flashes each time it rotates.
The star itself is only about 25 km across but contains the mass of nearly 1 million Earths.
Professor Andrew Lyne and his team from The University of Manchester report on a steady change in these flashes during a 22-year experiment watching the star, telling them about its very strong magnetic field and helping them learn about the otherwise-inaccessible star's interior.
The new observations show that the spacing of these pairs of pulses is increasing by 0.6 degrees per century, an unexpectedly large rate of evolution.
The astronomers employed a 42-ft telescope that was formerly used to track the Blue Streak missile at the Woomera Rocket Test Range in Australia until 1981, when it was dismantled, transported and re-erected at the Jodrell Bank Observatory in Cheshire, England.
This relatively modest telescope has been used to observe the Crab pulsar almost daily for 31 years, during which time the pulsar has rotated 30 billion times, and Jodrell Bank has kept count of every rotation. The most accurate observations, made since 1991, show the small gradual change in the pulse spacing.
Co-author Professor Sir Francis Graham Smith said that the 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.
The study has been published in the journal Science today.
--ANI (Posted on 02-11-2013)