Pulsar Puzzles Scientists; Star with a Multiple Personality Disorder

And you thought stars couldn't have multiple personality disorders. Scientists have discovered a strange, spinning star that is spontaneously switching between emitting strong X-rays and radio waves. Although radio frequencies are known to vary as stars change personalities, this is the first star that is known to switch between X-rays and radio waves.

The star, called a pulsar, is officially named PSR B0943+10 and is located about 3000 light-years away from Earth. It's five million years old, and whips through a rotation about once every 1.1 seconds. In addition, it emits a weak X-ray signal as charged particles radiate along magnetic lines and bombard magnetic poles.

Wim Hermsen of the Netherlands Institute for Space Research and the University of Amsterdam and his team were interested in knowing whether the X-rays from this particular star varied between two modes--such as the radio pulses in other stars. Using a European Space Agency X-ray space telescope, the scientists examined the pulsar and then combined their observations with work done at ground telescopes in the Netherlands and India.

What they found was more unusual than they expected. The star switched between emitting radio waves and X-rays, showing two distinct personalities. The personalities would change about once every few hours. In addition, these switches implied large changes in the star's magnetosphere. What drives these changes, though, is uncertain.

Hermsen and his team plan to compare the pulsar with similar objects in an attempt to predict the X-ray emission behavior. In addition, they plan to look at another pulsar later this year.

Their research was published in the journal Science.