Astronomers Discover a 'Transformer' Pulsar After Decades [VIDEO]
A team of international scientist has made a major achievement by discovering a millisecond pulsar that carries dual identities.
In the history of science such a millisecond pulsar with dual identities has never been observed earlier and it was done by a collection of orbiting X-ray telescopes that include NASA's Swift and Chandra X-ray Observatory.
According to the scientists, the star readily moves to and fro between two mutually exclusive styles of pulse emission. The two emissions consist of X rays and radio. It took the scientist's years to discover the transitional phase in the life of these powerful objects.
"This transitional object took us decades to find, and it provides us with a unique opportunity to observe a pulsar's intense magnetic field in action," Sergio Campana, an astronomer at Brera Observatory in Merate, Italy, and a co-author of a paper said in a news release.
The rise and fall of the gases flowing onto the pulsar from a normal companion star is what causes the sudden movement from X-rays to radio and back to X-rays.
A highly magnetized, rotating neutron star that releases a regular beam of light is defined as a 'pulsar'. Neutron stars with short regular rotational periods are very dense in nature and they generate an accurate interval between pulses that vary from millisecond to second for an individual pulsar. These millisecond pulsars are formed when they snack on the material emitted from a companion star, merge the density and magnetic fields with severe radiation. The fastest one recorded spins at 43,000 revolutions per minute. The astronomers hint toward the pulsars that are present in the binary system with normal stars for such rapid rotation.
During the stellar stage, the gas emitted from the normal star streams onto the neutron star, which immediately heats upto several million degrees during which they produce X-rays. The gas moving toward the pulsar is directed by the pulsar's magnetic field on to magnetic poles thereby creating hot spots that spin along with the neutron star and produce normal X-ray pulses. The gas then rushes to the surface of the pulsar producing X-rays and during this process the neutron star is coated with a layer of hydrogen and helium fuel.
X-Ray pulses come to an end after a billion of years when the flow of gas from the normal star falls and eventually ends. But radio emission produced due to the intense spin and magnetic field forces the neutron star continue as a radio pulsar.
The astronomers identified the X-ray transient on March 28 from an object dubbed IGR J18245-2452. It was detected by the European Space Agency's International Gamma Ray-Astrophysics Laboratory using Swift's X-Ray Telescope (XRT).
"Swift provided the first accurate, subarcminute localization of the X-ray burst, which allowed for the additional discovery of the pulsar's radio waves by the Australia Telescope Compact Array (ATCA)," said Jamie Kennea, a Swift team member at Penn State.
ESA's XMM-Newton satellite directed towards IGR J18245-2452 detected the presence of X-ray pulses. Further analysis claimed that the pulsar was merged by a companion star that is less than one fifth the mass of the Sun. Every 11 hours the two stars orbit each other.
"Swift's Burst Alert Telescope was dynamically triggered by X-ray bursts from this star, which allowed its XRT to rapidly confirm the thermonuclear character of this explosion," said John Nousek, professor of astronomy and astrophysics and director of the Swift Mission Operations Center at Penn State, which controls the spacecraft's science and flight operations.
NASA's Chandra observatory successfully located the source of X-ray but radio observation could not detect radio emissions. According to the astronomers, it takes million year timescales for such changes to occur.
The details of the object appear in the Sept. 26 issue of the journal Nature.