This star's capricious behavior appears to be fueled by a nearby companion star and may give new insights into the birth of millisecond pulsars, the astronomers said.
"What we're seeing is a star that is the cosmic equivalent of 'Dr. Jekyll and Mr. Hyde,' with the ability to change from one form to its more intense counterpart with startling speed," Scott Ransom, an astronomer at the National Radio Astronomy Observatory (NRAO) in Charlottesville, Virginia said.
"Though we have known that X-ray binaries -- some of which are observed as X-ray pulsars -- can evolve over millions of years to become rapidly spinning radio pulsars, we were surprised to find one that seemed to swing so quickly between the two," he said.
Neutron stars are the superdense remains of massive stars that have exploded as supernovas.
This particular neutron star, dubbed IGR J18245-2452, is located about 18,000 light-years from Earth in the constellation Sagittarius in a cluster of stars known as M28.
It was first identified as a millisecond radio pulsar in 2005 with the National Science Foundation's Robert C. Byrd Green Bank Telescope (GBT) and then later rediscovered as an X-ray pulsar by another team of astronomers in 2013.
The two teams eventually realized they were observing the same object, even though it was behaving very differently depending on when it was observed.
Additional observations and archival data from other telescopes confirmed the on-again, off-again cycle of X-ray and radio pulsations.
The study is published in the journal Nature.
--ANI (Posted on 30-09-2013)